vibrational ultra strong coupling of water and ice
TRANSCRIPT
doi.org/10.26434/chemrxiv.9808508.v1
Vibrational Ultra Strong Coupling of Water and IceHidefumi Hiura, Atef Shalabney, Jino George
Submitted date: 12/09/2019 • Posted date: 13/09/2019Licence: CC BY-NC-ND 4.0Citation information: Hiura, Hidefumi; Shalabney, Atef; George, Jino (2019): Vibrational Ultra Strong Couplingof Water and Ice. ChemRxiv. Preprint.
Water is of vital importance for life and human activities on Earth—it exhibits unique properties due to itsinterlinked and multipoint hydrogen bonding network. Here, we experimentally show that water can undergovibrational ultra strong coupling (V-USC) in both the liquid and solid forms when the OH stretching mode ofwater or ice is resonantly coupled with an optical mode of an infrared Fabry−Pérot cavity. The light-coupledH2O under V-USC reveals the largest Rabi splitting ever reported, reaching 22% and 26% of the vibrationalenergy for water and ice, respectively. We confirm that the extraordinarily large Rabi splitting stems from thedensely packed minuscule molecular structures, large vibrational energies, and broad and intenseabsorptions due to intermolecular hydrogen bonding. These new findings offer a brand-new platform inpolaritonic chemistry for controlling the properties of water with an ultra strong light-matter interaction.
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1
Vibrational Ultra Strong Coupling of Water and Ice
Hidefumi Hiura,*1 Atef Shalabney,2 and Jino George3 1System Platform Research Laboratories, NEC Corporation, 34 Miyukigaoka, Tsukuba, Ibaraki 305-8501 2 Physics and Optical Engineering Department, Braude College, Snunit St 51, Karmiel, 2161002, Israel 2 Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER), Mohali, Punjab-140306, India
*E-mail: [email protected]
Abstract
Water is of vital importance for life and human activities on Earth—it exhibits unique properties due to its interlinked and multipoint hydrogen bonding network. Here, we experimentally show that water can undergo vibrational ultra strong coupling (V-USC) in both the liquid and solid forms when the OH stretching mode of water or ice is resonantly coupled with an optical mode of an infrared Fabry−Pérot cavity. The light-coupled H2O under V-USC reveals the largest Rabi splitting ever reported, reaching 22% and 26% of the vibrational energy for water and ice, respectively. We confirm that the extraordinarily large Rabi splitting stems from the densely packed minuscule molecular structures, large vibrational energies, and broad and intense absorptions due to intermolecular hydrogen bonding. These new findings offer a brand-new platform in polaritonic chemistry for controlling the properties of water with an ultra strong light-matter interaction. Keywords: Vibrational Light-Matter Interaction, Vibro-Polariton, H2O
1. Introduction Vibrational strong coupling (V-SC) is a light-matter
interaction in which a vibrational mode of a molecule and an optical cavity mode are strongly coupled together in resonance, thereby creating a pair of vibro-polaritonic states, in other words, light-matter hybrid1,2 in the vibrational energy levels (Figure 1). The first observation of V-SC was the interaction of the C=O stretching band of poly(vinyl acetate) with a vacuum field (zero-point energy) of a Fabry‒Pérot (FP) cavity.3 Since then, many V-SC systems have been found in both solids and liquids using FP cavities4−17 and investigated theoretically.18−29 Among other findings, studies have also been shown that vibrational ultra strong coupling (V-USC) conditions can be achieved by coupling the C≡O stretching modes of liquid iron pentacarbonyl Fe(CO)5 (ΩR = 480 cm−1, ΩR: Rabi frequency) with the evolution of multiple vibro-polaritonic states.7 Del Pino et al. theoretically demonstrated that V-SC can be used to transform a Raman laser into an optical parametric oscillator.20 More recent reports cast light on polaritonic chemistry (or polariton chemistry),22−29 showing experimentally that V-SC or V-USC can exert a notable impact on chemical reactivity in bond-cleavage9,16,17 and hydrolysis reactions.15 Most recently, the novel concept of the vacuum-field catalysis (or cavity catalysis), which accelerates chemical reactions by vibrational light-matter coupling, has been reported experimentally15,17 and theoretically.30 In practice, the vacuum-field catalysis under V-USC can drastically enhance the hydrolysis reaction rate of cyanate ions (OCN‒) by 102 times and that of ammonia borane (NH3BH3) by 104 times. For these vacuum-field-catalyzed hydrolyses, the OH stretching mode of water is vibrationally coupled to an IR vacuum field in a FP cavity, and the resultant light-coupled water plays a key role as both a solvent and a reactant as if activated spontaneously under V-USC.15 Such vibrational light-matter interactions add a new dimension to molecular science and chemistry.1,26.
Figure 1. Scheme of vibrational light-matter coupling. The top, middle, and bottom rows show (a) sample configurations, (b) IR transmission spectra, and (c) energy diagrams. The left, middle, and right columns correspond to (i) water in a noncavity, (ii) water in an FP cavity, and (iii) an FP cavity without water.
Meanwhile, for decades, the unique nature of water and ice has been investigated by vibrational spectroscopy.31−37 In particular, OH stretching modes of water and ice are very sensitive probes in the IR region for clarifying the dynamic nature of the 3-D hydrogen bonding network.38−41 Here, we are trying to understand such systems in an unconventional way by coupling particular OH (OD) stretching vibrational transitions to IR vacuum fluctuations. In this letter, we first demonstrate the IR spectroscopic features of V-USC in water and ice molecules. Second, we reveal the origin of the giant vibrational Rabi splitting for light-coupled water and ice by quantitatively comparing the OH (OD) stretches with various vibrations of different molecular systems.
2. Experimental 2-1. Tuning of the Fabry-Pérot (FP) Cavity
The resonance condition of V-SC and V-USC using an FP cavity can be expressed as follows:3−5,7
𝜔 𝑖 𝑖𝑘 𝜔 , 𝑘102𝑛𝐿
1
where ωc(i) is the frequency of the ith optical mode in cm−1, i is a natural number, k0 is the free spectral range (FSR) in cm−1, ω0 is the vibrational frequency of the molecules in cm−1, n is the refractive index of the cavity medium, and L is the cavity length in µm. Because ω0 is an eigenvalue of molecules and n is usually fixed when the cavity medium is chosen, ωc(i) is tuned to ω0 by changing i and L: e. g., for the OH stretching of H2O water, L is tuned to be approximately 10.2 µm when i = 9 since ω0 = 3400 cm−1 and n ≈ 1.30. In practice, we adjusted L approximately with a plastic (Teflon) or metal (titanium) spacer with a thickness of 1 to 50 µm and tuned L finely by the micromotion of an internal cylinder equipped in a variable path length IR cell (International
2
Crystal Laboratories), thereby enabling us to observe V-SC and V-USC under the exact resonance conditions. 2-2. IR Spectra Measurements
We recorded the IR transmission and absorption spectra of samples under N2 with a 2 cm−1 resolution using an FT-IR spectrometer (FT/IR-6800, Jasco). Spectra of liquid samples were acquired at room temperature (~25 °C), while spectra of ice samples were measured a few degrees below the melting point. We equipped the spectrometer with the abovementioned IR cell consisting of a movable metal cylinder containing several-millimeter-thick parallel windows made of zinc selenide or sapphire, both of which are rather transparent in the region of the OH and OD stretching vibrations. We sandwiched liquid samples between the parallel windows and sealed liquid samples with a spacer. Ice was made from liquid water in the IR cell by cooling with a flowing coolant from a chiller kept at a temperature of −20 ºC. The FP cavity comprises a pair of 10-nm-thick gold mirrors sputtered on the inner surfaces of the parallel windows. The typical FP cavity gave a quality factor of Q ≈ 55 ± 15. To prevent direct contact of samples with the gold mirrors, we covered the mirrors with a 100-nm-thick SiO2 layer derived from perhydropolysilazane (NN110-20, Merck Ltd.).
2-3. Materials We used ultrapure water of semiconductor grade and
deuterium oxide (heavy water, D2O, 99.9 atom % D) purchased from Wako Pure Chemical Industries, Inc.; alcohols purchased from Kanto Chemical Co. Inc.; chloroform-d1 (CDCl3, 99.8 atom % D), methanol-d4 (CD3OD, 99.8 atom % D), phenyl isocyanate, and phenyl isothiocyanate purchased from Tokyo Chemical Industry Co., Ltd.; and acetonitrile, benzene, cyclohexane, chloroform, N,N-dimethylformamide, and toluene purchased from Sigma-Aldrich Japan. All the compounds were used without any further purification.
When measuring IR spectra of H2O (D2O) water and ice with various concentrations C, we diluted H2O (D2O) water by adding D2O (H2O) water to maintain the same hydrogen bonding environment as much as possible. The mixing of H2O and D2O water gives an equilibrium of H2O + D2O 2HDO with an equilibrium constant Ke = [HDO]2/[H2O][D2O] = 4.16 ± 0.30.34 If the initial concentrations of H2O and D2O are respectively given as [H2O]0 and [D2O]0, the following equalities hold for any [H2O]0 and [D2O]0: C = [H2O] + 1/2[HDO] = [H2O]0 for H2O water, and C = [D2O] + 1/2[HDO] =[D2O]0 for D2O water.
Figure 2. Dependence of the Rabi frequency ΩR of light-coupled OH (OD) stretch oscillators in water and ice on concentration C. (a) to (d) Comparison of IR transmittance spectra of light-coupled H2O (D2O) water and ice at various C. In (a) to (d), (i) is a series of IR spectra of pure and diluted H2O (D2O) water or ice in a cell without an FP cavity, whereas each spectrum from (ii) to (vi) was measured with an FP cavity when C was changed in decrements of 0.2C0 (C0: pristine concentration). All the spectra are normalized to unity. (e) Rabi frequency ΩR vs. relative concentration 𝐶/𝐶 for water and ice.
(d)(c)
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0.2C0
k9
k6
k5
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k5
k5k8
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k5
(i)
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3
Figure 3. Dependence of the Rabi frequency ΩR of light-coupled OH (OD) stretch oscillators in water and ice on optical mode number i. (a) to (d) Comparison of IR transmittance spectra of light-coupled H2O (D2O) water and ice with various i. In (a) to (d), (i) is a series of IR spectra of pure and diluted H2O (D2O) water or ice in a cell without an FP cavity, whereas each spectrum from (ii) to (vi) was measured with an FP cavity when using various optical modes. All the spectra are normalized to unity. (e) Rabi frequency ΩR vs. optical mode number i for water and ice.
3. Results and Discussion
3-1. Principle of vibrational light-matter coupling Figure 1 schematically outlines the vibrational light-matter
coupling of water to an FP cavity. In brief, as shown in row (b), a pair of Rabi splitting appears when the OH stretching mode of water is vibrationally coupled with a given optical mode of an FP cavity under the resonant condition of ω0 = ωc, where ω0 is the fundamental vibrational frequency of the OH stretch and ωc is the frequency of one of the cavity modes. The difference in energy between the upper P+ and lower P− polaritonic states is called as the vacuum Rabi splitting energy ℏΩR, and given by1,2,5
ℏΩ 2√𝑁𝐸𝑑 2√𝑁ℏ𝜔2𝜀 𝑉
𝑑 𝑛 1 2
where N is the number of molecules, E is the amplitude of the electric field of light, d is the transition dipole moment of the molecules, nph is the number of photons populating the cavity mode, ε0 is the dielectric constant of a vacuum, and V is the mode volume. The coupling ratio is defined as half of the ratio of ΩR to ω0; that is, ΩR/2ω0.42,43 This normalized form is convenient for comparing light-matter coupling having energies of different scales. The boundary between the strong and ultra strong coupling regimes is most often drawn at ΩR/2ω0 = 0.1.26,42‒45
3-2. Dependence of ΩR of Light-Coupled OH (OD) Stretch Oscillators in Water and Ice on Their Concentrations
Figures 2a to 2d compare the IR spectra of light-coupled OH (OD) stretch oscillators in H2O (D2O) water and ice with various concentrations C, where H2O (D2O) was diluted by D2O (H2O) to keep the same hydrogen bonding environment as is in pristine H2O (D2O). On the one hand, the OH stretches of H2O water (3400 cm−1) and H2O ice (3280 cm−1) were respectively coupled to the 9th and 7th optical modes of an FP cavity, thereby forming pairs of vibro-polaritonic states P9+/P9− and P7+/P7‒. On the other hand, the OD stretches of D2O water (2500 cm−1) and D2O ice (2450 cm−1) were respectively coupled to the 7th and 5th optical modes of an FP cavity, thereby forming pairs of P7+/P7− and P5+/P5‒. The measured ΩR was approximately 740 cm−1 for pure H2O water, 540 cm−1 for pure D2O water, 820 cm−1 for pure H2O ice, and 600 cm−1 for pure D2O ice. All the ΩR values are sufficiently larger than the inhomogeneous full width at half maximum (FWHM) for the original OH (OD) stretching modes—i.e., Γi ≈ 400 (300) cm−1 for water and Γi ≈ 320 (240) cm−1 for ice—and the FWHM for optical modes—i.e., ΓFP ≈ 100 cm−1—putting the system in the strong coupling regime.1,2 Furthermore, the dependence of ΩR on C confirms this finding (Figure 2e). The least-squares fits give ΩR/2ω0 = 0.113 for neat
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OH str. / H2O water OD str. / D2O water OH str. / H2O ice OD str. / D2O ice
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H2O water, 0.111 for neat D2O water, 0.129 for neat H2O ice and 0.123 for neat D2O ice, indicating that the observed vibrational Rabi splitting in pure water and ice occur in the ultra strong coupling regime because all the values surpass the aforementioned boundary criterion (ΩR/2ω0 ≥ 0.1).26,42‒45
Notably, ΩR/2ω0 for pure H2O ice, 0.129, is the largest ever reported in the literature (see inset of Figure 3b). Another notable feature in Figures 2a to 2d is that the FWHM values of the P± polariton bands for light-coupled water and ice, Γp± (e.g., Γp+ ≈ 40 cm−1, Γp− ≈ 80 cm−1 for pristine H2O water), are half an order of magnitude smaller than the original Γi values. This band-narrowing provides additional evidence that the observed phenomena arise from typical vacuum-field Rabi splitting because Γp± is determined not by Γi but rather by the homogeneous linewidth Γh when ΩR ≫ Γi, namely, in the strong coupling regime.46 3-3. Dependence of ΩR of Light-Coupled OH (OD) Stretch Oscillators in Water and Ice on Optical Mode Number
Figures 3a to 3d compare the IR spectra of OH (OD) stretching oscillators in pure H2O (D2O) water and ice coupled with various optical modes. On the one hand, the OH stretching at 3400 cm−1 of H2O water was coupled to the k2, k4, k10, k23, and k48 optical modes, whereas the OH stretching at 3280 cm−1 of H2O ice was coupled to the following ones: k1, k5, k11, k25, and k40. On the other hand, the OD stretching at 2500 cm−1 of D2O water was coupled to the k3, k4, k7, k11, and k36 optical modes, whereas the OD stretching at 2450 cm−1 of D2O ice was coupled to the following ones: k1, k5, k9, k16, and k35. The optical modes were arbitrarily chosen for demonstration. The most clear-cut aspect of Figs. 3a to 3d is that ΩR is independent of the optical mode number i. Figure 3e gives ΩR/2ω0 = 0.112 for H2O water, 0.109 for D2O water, 0.127 for H2O ice, and 0.123 for D2O ice by least-squares fitting. All these values are in excellent agreement with those obtained from Fig. 2e. Another noteworthy point in Figs. 3a to 3d is that the OH (OD) stretch modes of water and ice tend to couple with only a single optical mode. This tendency is true even though FSR k0 is much smaller than ΩR. It is as if P+ and P‒ vibro-polaritonic states expel uncoupled optical modes from the energy region between them. Consequently, as manifested in Figs. 3a to 3d, optical mode bands are more tightly packed as they are closer to P± bands. Similar shifts of optical mode bands around P± bands are also observed in Figs. 2a to 2d. The amount of such shifts in optical mode band is apt to be proportional to the magnitude of ΩR. 3-4. Analyses of Key Factors Determining ΩR
We now discuss the origins of the giant ΩR observed for OH (OD) stretching oscillators in water and ice. For this purpose, we focus on two key factors, concentration C and oscillator strength (or f-value) fosc, that determine ΩR in theory: according to Eq. (2), ΩR is proportional to the square root of C times fosc because fosc is defined with d and ω0 as follows:47,48
𝑓4π𝑚3𝑒 ℏ
𝜔 𝑑 4.702 10 cm ∙ D 𝜔 𝑑 3
where me is the mass of an electron, e is the elementary charge, and unit D is in debye. Figure 4a depicts ΩR plotted against
𝐶𝑓 for the light-coupled OH (OD) stretches of water and ice when gradually diluted. Note that almost all the plots of the four concentration dependences lie on a single straight line with a slope of 7.31×103 [mol−0.5∙dm1.5∙cm−1], confirming that the aforementioned relation, Ω ∝ 𝐶𝑓 , is experimentally valid at least for the light-coupled OH (OD) stretches of water and ice. In addition, the ΩR/2ω0 values are scaled together with
𝐶𝑓 /𝜔 , as shown in the inset of Figure 4a. We next compare OH (OD) stretching oscillators in water and ice with other molecular oscillators. Figure 3b presents ΩR versus 𝐶𝑓 for various light-coupled vibrational modes, including stretches and bends (or deformations) of diverse molecules (see Tables S1 to S3 for details). The values of ΩR were arranged in the order of lowest to highest as follows: (1) the OH (OD) stretches of pristine ice and water (circles in red), (2) the OH (OD) stretches of pristine alcohols (triangles in blue), (3) other vibrational modes of pristine molecular liquids (rhombuses in green) and the OH (OD) bends of pristine water (squares in yellow). The overall proportionality of ΩR to 𝐶𝑓 is surprisingly good considering that the plotted data were obtained from different types of vibrations among different molecules. The least-squares fitted line in Figure 4b is
Ω 7.32 10 mol . ∙ dm . ∙ cm 𝐶𝑓 4
The slope of Eq. (4) is in an excellent match with that obtained from Figure 4a, as expected from Eq. (2). The empirical formula of Eq. (4) will be useful for future studies to predict the ΩR of vibrational light-matter coupling. The coupling ratio ΩR/2ω0 versus 𝐶𝑓 /𝜔 , as shown in the inset of Figure 4b, demonstrates the largest ΩR/2ω0 ever reported for liquid V-SC and V-USC.
Figure 4. Analyses of key factors determining Rabi frequency ΩR. (a) ΩR vs. 𝐶𝑓 for light-coupled OH (OD) stretching of water and ice. The unit of concentration C is mol∙dm−3, whereas the oscillator strength fosc is dimensionless. The plotted data were taken from Figures 2 and Table S1. (b) ΩR vs. 𝐶𝑓 for various light-coupled vibrational modes. The plotted data were taken from Tables S1 to S3. In (a) and (b), each inset shows ΩR/2ω0 vs. 𝐶𝑓 /𝜔 .
0.03 0.06 0.09 0.120
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(a)
(b)
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3-5. Comparison of vibrational modes in water and other compounds on the basis of C and fosc.
Figure 5 compares water and other compounds on the basis of C and fosc. Considering that the larger the values of C and fosc
are, the larger ΩR becomes, the plots of the OH (OD) stretches of water and ice occupy the best position with C = 51−55 mol∙dm−3 and fosc = (1−3)×10‒4 to maximize ΩR. On the one hand, the OH (OD) stretches of alcohols have C values (4−25 mol∙dm−3) much smaller than those of water and ice, although they have fosc values ((1−3)×10‒4) as large as those of water and ice. On the other hand, the OH (OD) bends of water possess fosc values of (0.4−1)×10‒5 much smaller than those of the OH (OD) stretches, although they possess C values of 55 mol∙dm−3 that are the same as those of the OH (OD) stretches of water. Furthermore, the fosc values of the other molecular oscillators range widely from approximately 10‒6 to 10‒3, whereas their C values never exceed 25 mol∙dm−3 and are normally found around 10 mol∙dm−3. These analyses show that among molecular vibrations in liquids, the OH (OD) stretches of water and ice have the highest combination of large C and fosc values.
Figure 5. Two-dimensional map of C and fosc for various vibrational modes on a double logarithmic scale. The plotted data were the same as those in Figure 4b.
The reason why the OH (OD) stretching modes of water and ice have such enormously large C values and considerably large fosc values is as follows: First, the by far largest C is derived from the fact that water and ice are densely packed with an extremely compact structure of H2O (D2O) molecules. To our knowledge, H2O (D2O) water and ice exhibit some of the highest C values among all the molecules under standard conditions. Second, the large fosc values of the OH (OD) stretches of water and ice originate from intermolecular hydrogen bonding, which can enhance fosc by a factor of 26 and 38 when water vapor condenses to liquid water and ice, respectively.33,38‒40 This situation is in sharp contrast with the general trend for the other molecular vibrations because in general, the ratio of fosc in the liquid phase to that in the gas phase is described as (n + 2)2/9n (n: refractive index of molecular liquid),31,33 the value of which is no more than two because n < 2 for normal molecular liquids. The intermolecular hydrogen bonding also explains why the OH (OD) stretches of alcohols are second to those of ice and water in the size order of ΩR since the fosc enhancement is also found for OH (OD) stretches of alcohols.31,40 Thus, hydrogen bonding plays an implicit but indispensable role in enhancing ΩR for light-coupled OH (OD) stretching oscillators. Overall, we can summarize that the enormous ΩR values for light-coupled OH (OD) stretching oscillators of water and ice can be attributed to
the following three factors: (1) their extremely compact molecular structures, (2) large vibrational energies, (3) broad and intense absorptions due to intermolecular hydrogen bonding.
4. Conclusion
We have shown that the OH vibration of water and ice can be hybridized with a cavity mode to generate new vibro-polariton states with new features. We have proved that the light-coupled OH (OD) oscillators in water and ice can be explained by the general theory of vacuum Rabi splitting. We have clarified that their exceptionally large coupling ratio ΩR/2ω0, 0.11–0.13, stems from their extremely compact molecular structures, their large vibrational energies, and their broad and intense absorptions due to intermolecular hydrogen bonding. We envision that the giant splitting between the new hybrid states should influence the fundamental properties of water and ice, as most typified by the high-speed hydrolysis in V-USC water.15 Such substantial alteration of the ground state landscape holds promise for polaritonic chemistry and vacuum-field catalysis. Acknowledgement
H.H., J.G., and A.S. acknowledge Professor Thomas W. Ebbesen for valuable discussions, and H.H. thanks Dr. Jingwen Lu for experimental assistance. References 1. T. W. Ebbesen, Acc. Chem. Res. 2016, 49, 2403–2412. 2. P. Törmä, W. L. Barnes, Rep. Prog. Phys. 2015, 78, 013901. 3. A. Shalabney, J. George, J. A. Hutchison, G. Pupillo, C.
Genet, T. W. Ebbesen, Nat. Comm. 2015, 6, 5981. 4. A. Shalabney, J. George, H. Hiura, H.; J. A. Hutchison, C.
Genet, P. Hellwig, T. W. Ebbesen, Angew. Chem. Int. Ed. 2015, 54, 7971–7975.
5. J. George, A. Shalabney, J. A. Hutchison, C. Genet, T. W. Ebbesen, J. Phys. Chem. Lett. 2015, 6, 1027–1031.
6. J. P. Long, B. S. Simpkins, ACS Photonics 2015, 2, 130–136.
7. J. George, T. Chervy, A. Shalabney, E. Devaux, H. Hiura, C. Genet, T. W. Ebbesen, Phys. Rev. Lett. 2016, 117, 153601.
8. R. M. A. Vergauwe, J. George, T. Chervy, J. A. Hutchison, A. Shalabney, V. Y. Torbeev, T. W. Ebbesen, J. Phys. Chem. Lett. 2016, 7, 4159–4164.
9. A. Thomas, J. George, A. Shalabney, M. Dryzhakov, S. J. Varma, J. Moran, T. Chervy, X. Zhong, E. Devaux, C. Genet, J. A. Hutchison, T. W. Ebbesen, Angew. Chem. Int. Ed. 2016, 55, 11462–11466.
10. D. Dunkelberger, B. T. Spann, K. P. Fears, B. S. Simpkins, J. C. Owrutsky, Nat. Comm. 2016, 7, 13504.
11. M. Hertzog, P. Rudquist, J. A. Hutchison, J. George, T. W. Ebbesen, K. Börjesson, Chem. Eur. J. 2017, 23, 18166–18170.
12. B. Xiang, R. F. Ribeiro, A. D. Dunkelberger, J. Wang, Y. Lia, B. S. Simpkins, J. C. Owrutsky, J. Yuen-Zhou, W. Xiong, Proc. Natl. Acad. Sci. USA 2018, 115, 4845–4850.
13. V. F. Crum, S. R. Casey, J. R. Sparks, Phys. Chem. Chem. Phys. 2018, 20, 850–857.
14. H. Hiura, Bull. Solid State Phys. Appl. 2018, 24, 9–14. 15. H. Hiura, A. Shalabney, J. George, 2018, ChemRxiv
preprint. https://doi.org/10.26434/chemrxiv.7234721.v1. 16. A. Thomas, L. Lethuillier-Karl, K. Nagarajan, R. M. A.
Vergauwe, J. George, T. Chervy, A. Shalabney, E. Devaux, C. Genet, J. Moran, T. W. Ebbesen, Science 2019, 363, 615–619.
17. J. Lather, P. Bhatt, A. Thomas, T. W. Ebbesen, J. George, Angew. Chem. Int. Ed. 10.1002/anie.201905407.
10−6 10−5 10−4 10−3
100
101
102
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tra
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n:
C /
mo
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Oscillator strength: fosc
OH (OD) str. / water & ice OH (OD) str. / alcohols HOH (DOD) bend / water Other vibrational modes
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18. J. del Pino, J. Feist, F. J. Garcia-Vidal, New J. Phys. 2015, 17, 053040.
19. J. del Pino, J. Feist, F. J. Garcia-Vidal, J. Phys. Chem. C 2015, 119, 29132–29137.
20. J. del Pino, F. J. Garcia-Vidal, J. Feist, Phys. Rev. Lett. 2016, 117, 277401.
21. J. Flick, M. Ruggenthaler, H. Appel, A. Rubio, Proc. Natl. Acad. Sci. USA 2017, 114, 3026–3034.
22. J. Galego, F. J. Garcia-Vidal, J. Feist, Phys. Rev. Lett. 2017, 119, 136001.
23. L. A. Martínez-Martínez, R. F. Ribeiro, J. Campos-González-Angulo, J. Yuen-Zhou, ACS Photonics 2018, 5, 167–176.
24. R. F. Ribeiro, L. A. Martínez-Martínez, M. Du, J. Campos-Gonzalez-Angulo, J. Yuen-Zhou, Chem. Sci. 2018, 9, 6325-6339.
25. J. Galego, C. Climent, F. J. Garcia-Vidal, J. Feist, 2018, arXiv preprint arXiv:1807.10846v1 [quant-ph].
26. F. Kockum, A. Miranowicz, S. De Liberato, S. Savasta, F. Nori, Nat. Rev. Phys. 2019, 1, 19–40.
27. S. Kéna-Cohen, J. Yuen-Zhou, ACS Cent. Sci. 2019, 5, 386–388.
28. J. Yuen-Zhoua, V. M. Menonb, Proc. Natl. Acad. Sci. USA 2019, 116, 5214–5216.
29. J. Campos-Gonzalez-Angulo, R. F. Ribeiro, J. Yuen-Zhou, 2019, arXiv preprint arXiv:1902.10264 [physics.chem-ph].
30. H. Hiura, A. Shalabney, 2019, ChemRxiv. Preprint. https://doi.org/10.26434/chemrxiv.9275777.v1.
31. S. Wexler, Appl. Spectrosc. Rev. 1967, 1, 29–98. 32. S. Ikawa, S. Maeda, Spectrochim. Acta A 1967, 24, 655–
665.
33. J. E. Bertie, M. K. Ahmed, H. H. Eysel, J. Phys. Chem. 1989, 93, 2210–2218.
34. J.-J. Max, C. Chapados, J. Chem. Phys. 2002, 116, 4626. 35. J.-J. Max, C. Chapados, J. Chem. Phys. 2009, 131, 184505. 36. S. Y. Willow, M. A. Salim, K. S. Kim, S. Hirata, Sci. Rep.
2015, 5, 14358. 37. F. Perakis, L. De Marco, A. Shalit, F. Tang, Z. R. Kann, T.
D. Kühne, R. Torre, M. Bonn, Y. Nagata, Chem. Rev. 2016, 116, 7590–7607.
38. J. E. Lowder, J. Quant. Spcctrosc. Radiat. Transf. 1971, 11, 153–159.
39. E. Whalley, D. D. Klug, J. Chem. Phys. 1986, 84, 4807–4809.
40. B. Athokpam, S. G. Ramesh, R. H. McKenzie, Chem. Phys. 2017, 488–489, 43–54.
41. M. Chaplin, 2007, arXiv preprint arXiv:0706.1355 [cond-mat.soft].
42. C. Ciuti, G. Bastard, Phys. Rev. B 2005, 72, 115303. 43. S. J. Bosman, M. F. Gely, V. Singh, A. Bruno, D. Bothner,
G. A. Steele, npj Quantum Inf. 2017, 3, 46. 44. J. Casanova, G. Romero, I. Lizuain, J. J. García-Ripoll, E.
Solano, Phys. Rev. Lett. 2010, 105, 263603. 45. X. Cao, J. Q. You, H. Zheng, F. Nori, New J. Phys. 2011,
13, 073002. 46. R. Houdre´, R. P. Stanley, M. Ilegems, Phys. Rev. A 1996,
53, 2711. 47. H. G. Kjaergaard, B. R. Henry, J. Chem. Phys. 1992, 96,
4841–4851. 48. Y. Chen, Y. Morisawa, Y. Futami, M. A. Czarnecki, H.-S.
Wang, Y. Ozaki, J. Phys. Chem. A 2014, 118, 2576–2583
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1
Vibrational Ultra Strong Coupling of Water and Ice
Hidefumi Hiura,*1 Atef Shalabney,2 and Jino George3
1System Platform Research Laboratories, NEC Corporation, 34 Miyukigaoka, Tsukuba, Ibaraki 305-8501
2 Physics and Optical Engineering Department, Braude College, Snunit St 51, Karmiel, 2161002, Israel
2 Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER), Mohali,
Punjab-140306, India
*E-mail: [email protected]
Table of contents Key parameters of vibrational Rabi splitting:
Table S1. Key parameters of vibrational Rabi splitting for water and ice.
Table S2. Key parameters of vibrational Rabi splitting for alcohols.
Table S3. Key parameters of vibrational Rabi splitting for various molecular liquids
2
Key parameters of vibrational Rabi splitting
In Tables S1 to S3, we summarized some key parameters of vibrational Rabi splitting discussed in the main text. All numerical values of oscillator strength fosc were obtained from the literature reported cited in the last columns of the tables. Most studies gave the integrated intensity A instead of fosc for the given vibrational mode. The A values vary from literature to literature because of the multiplicity of units such as cm−2∙mol−1∙dm3, km∙mol−1, and cm2∙mol−1. We thus converted A to fosc using appropriate multipliers:31,47,50,63 e.g., for A recorded in decadic logarithm in the units of cm−2∙mol−1∙dm3, A was converted to fosc with a multiplier of 4.315×10−9/gdeg, where gdeg is the degeneracy of the vibrational mode.63 Similarly, for A in the units of km∙mol−1, A was converted to fosc with a multiplier of 1.876×10−7/gdeg.47 While most of the examined vibrational modes, including the OH (OD) stretches and bends of water and ice, are not degenerated, some degenerate modes are found in the following IR bands: the C≡O stretch (E’) of Fe(CO)5, the C−H stretch (Eu) and the C−H bend (Eu) of cyclohexane, the C−Cl stretches (E) of chloroform and chloroform-d1, and the C=C stretch + C−H bend (E1u) of benzene, where symbols in parentheses denote the symmetry species of the corresponding vibrational modes.
Table S1. Key parameters of vibrational Rabi splitting for water and ice.
molecule vibrational mode
ω0 [cm−1] fosc×10−5 C0
[molꞏdm−3] ΩR [cm−1] ΩR/2ω0 remarks
H2O ice O−H str. 3250 26.2[a] 50.9 820 0.128 [a], Ref. [33]
H2O water O−H str. 3400 18.1[a] 55.3 740 0.113 [a], Ref. [32]
D2O ice O−D str. 2450 13.6[b] 50.8 600 0.123 [b], Ref. [33]
D2O water O−D str. 2500 9.51[b] 55.1 540 0.111 [b], Ref. [32]
H2O water O−H bend 1645 1.00[a] 55.3 170 0.0515 [a], Ref. [32]
D2O water O−D bend 1210 0.401[a] 55.1 120 0.0488 [a], Ref. [32]
Table S2. Key parameters of vibrational Rabi splitting for alcohols.
molecule vibrational mode
ω0 [cm−1] fosc×10−5 C0
[molꞏdm−3] ΩR [cm−1] ΩR/2ω0 remarks
glycerol O−H str. 3350 30.6[a] 13.7 498 0.0749 [a], Ref. [49]
ethylene glycol O−H str. 3350 20.4[a] 17.9 474 0.0713 [a], Ref. [49]
propylene glycol O−H str. 3350 20.4[a] 13.6 434 0.0651 [a], Ref. [49]
methanol O−H str. 3350 11.4[b] 24.7 426 0.0636 [b], Ref. [50]
ethanol O−H str. 3350 9.30[c] 17.1 352 0.0525 [c], Ref. [51]
2-propanol O−H str. 3350 9.44[c] 13.0 317 0.0474 [c], Ref. [51]
methanol-d4 (CD3OD) O−D str. 3350 7.97[b] 24.6 302 0.0609 [b], Ref. [50]
t-butyl alcohol O−H str. 3350 9.04[d] 10.5 301 0.0449 [d], Ref. [53]
1-hexanol O−H str. 3350 9.11[c] 7.98 248 0.0372 [c], Ref. [51]
terpineol O−H str. 3350 9.07[e] 6.06 196 0.0289 [e], Ref. [53]
1-docecanol O−H str. 3350 9.07[e] 4.46 148 0.0223 [e], Ref. [53]
3
Table S3. Key parameters of vibrational Rabi splitting for various molecular liquids
molecule vibrational mode
ω0 [cm−1] fosc×10−5 C0
[molꞏdm−3] ΩR [cm−1] ΩR/2ω0 remarks
Fe(CO)5 C≡O str. 2000[a] 72.9[b] 7.40 480[a] 0.120 [a], Ref. [7] [b], Ref. [54]
phenyl isothiocyanate N=C=S str. 2083 30.6[c] 8.35 309 0.0742 [c], Ref. [31]
phenyl isocyanate
N=C=O str. 2272 28.1[c] 9.17 308 0.0678 [c], Ref. [31]
carbon disulfide S=C=S str. 1520[d] 13.4[e] 16.6 287[d] 0.0944 [d], Ref. [7]
[e], Ref. [55]
N,N’-dimethyl formamide C=O str. 1658 6.41[f] 13.0 215 0.0651 [f], Ref. [56]
cyclohexane C−H str. 2917 12.4[g] 9.26 199 0.0342 [g], Ref. [51]
1-dodecanol C−H str. 2901 19.4[h] 4.46 190 0.0328 [h], Ref. [31]
methanol C−O str. 1037 1.90[i] 24.7 170 0.0820 [i], Ref. [50]
acetone C=O str. 1732 3.99[j] 13.5 148 0.0427 [j], Ref. [48]
chloroform C−Cl str. 764 2.03[k] 12.5 147 0.0960 [k], Ref. [48]
chloroform-d1 (CDCl3) C−Cl str. 738 1.36[k] 12.5 130 0.0879 [k], Ref. [58]
hexanal C=O str. 1727[l] 3.34[l] 8.14 105[l] 0.0304 [l], Ref. [58]
chloroform-d1 (CDCl3) C−D bend 914 1.88[k] 12.5 95.0 0.0520 [k], Ref. [58]
toluene C−H str. 3041 2.76[m] 9.41 86.8 0.0143 [m], Ref. [59]
1-dodecanol C−H bend 1450 1.05[h] 4.46 58.3 0.0201 [h], Ref. [31]
chloroform C−H bend 1217 0.566[k] 12.5 56.4 0.0232 [k], Ref. [58]
benzonitrile C≡N str. 2229 0.900[n] 9.79 54.0 0.0121 [n], Ref. [60]
cyclohexane C−H bend 1436 0.597[l] 9.26 50.0 0.0173 [l], Ref. [57]
acetonitrile C≡N str. 2255[o] 0.393[o] 19.1 41.0[o] 0.00909 [o], Ref. [5]
benzene C=C str. + C−H bend 1477 0.233[p] 11.2 44.7 0.0303 [p], Ref. [61]
chloroform C−H str. 3025 0.146[q] 12.5 38.0 0.00630 [q], Ref. [62]
chloroform-d1 (CDCl3) C−D str. 2030 0.0635[q] 12.5 25.6 0.00630 [q], Ref. [62]
toluene C=C str. 1603 0.846[m] 9.41 22.2 0.00692 [m], Ref. [59]
References
49. M. A. Krest’yaninov, A. G. Titova, A. M. Zaichikov, Russ J. Phys. Chem. A, 2014, 88, 2114−2120.
50. J. E. Bertie, S. L. Zhang, H. H. Eysel, S. Baluja, M. K. Ahmed, Appl. Spectrosc. 1993, 47, 1100−1114.
51. H. H. Eysel, J. E. Bertie, J. Mol. Struct. 1986, 142, 227−230. 52. A. V. Iogansen, M. S. Rozenberg, J. Struct. Chem. 1989, 30, 76−83. 53. Smith, F. A.; Creitz, E. C. J. Res. Natl. Bur. Stand. 1951, 46, 145−164.
4
54. Jiang, Y.; Lee, T.; Rose-Petruck, C. G. J. Phys. Chem. A 2003, 107, 7524−7538. 55. Kakimoto, M.; Fujiyama, T. Bull. Chem. Soc. Jpn. 1972, 45, 2970−2974. 56. N. Biliškov, Spectrochim. Acta Part A 2011, 79, 302−307. 57. C. D. Keefe, J. E. Pickup, Spectrochim. Acta Part A 2009, 72, 947−953. 58. K. Kim, W. T. King, J. Chem. Phys. 1984, 80, 978−982. 59. J. E. Bertie, R. N. Jones, Y. Apelblat, C. D. Keefe, Appl. Spectrosc. 1994, 48, 127−143. 60. S. S. Andrews, S. G. Boxer, J. Phys. Chem. A 2000, 104, 11853−11863. 61. J. E. Bertie, R. N. Jones, C. D. Keefe, Appl. Spectrosc. 1993, 47, 891−911. 62. I. Kanesaka, T. Miyajima, K. Kawai, J. Mol. Struct. 1984, 116, 259−294. 63. Physical Methods for Chemists, 2nd ed.; R. S. Drago Ed.; Scientific Publishers: Gainesville,
1992; pp. 120−122. Author Contributions
A.S. and J.G. instructed H.H. in the experimental techniques of V-SC. H.H. planned the project of V-USC in water and ice. H.H acquired and analyzed the IR data. H.H. wrote the manuscript, and A.S. and J.G. revised it. All authors contributed to discussions.
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