sub-doppler spectroscopy of h 3 +
DESCRIPTION
Sub-Doppler Spectroscopy of H 3 +. James N. Hodges , Adam J. Perry, Brian M. Siller , Benjamin J. McCall. Outline. Motivation Fundamental Physics Astronomy Instrument Description Transition Frequency Results Wavelength Calibration Testing. H 3 + Fundamental Benchmark. - PowerPoint PPT PresentationTRANSCRIPT
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Sub-Doppler Spectroscopy of H3+
James N. Hodges, Adam J. Perry, Brian M. Siller, Benjamin J. McCall
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Outline
• Motivation– Fundamental Physics– Astronomy
• Instrument Description• Transition Frequency Results• Wavelength Calibration Testing
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H3+ Fundamental Benchmark
• Simplest polyatomic ion• Benchmark for ab initio theory
– Accuracy of order 300 MHz @ low energy
• QED corrections are frontier– Accuracy of order 30 MHz @ low energy
• Requires higher precision data
O. L. Polyansky, J. Tennyson, J. Chem. Phys. (1999), 110, 5056-5064.J. Komasa, et al. J. Chem. Theor. Comp. (2011), 7, 3105-3115.
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H3+ Astronomically Important
• Abundant in Interstellar Medium• Deuterium Fractionation• Found in Ionospheres of Gas
Giants• Measure Speed of Auroral Winds • Limited by Laboratory Accuracy
T. R. Geballe and T. Oka, Nature (1996), 384, 334.P. Drossart et al. Nature (1989), 340, 539.D. Rego et al. Nature (1999), 399, 121.
Images From: http://solarsystem.nasa.gov/planets/profile.cfm?Object=Jupiterhttp://www.ucl.ac.uk/~ucaptss/work/publications/royalsoc/energy.htm
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Spectroscopic TechniqueLarge Signal
Low Noise
Ion Selectivity
Cavity Enhancement
Heterodyne Spectroscopy
Velocity Modulation
NICE-OHVMS
Noise Immune Cavity Enhanced Optical Heterodyne Velocity Modulation Spectroscopy
B. M. Siller, et al. Opt. Express (2011), 19, 24822-7.
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Instrumental Layout
OPO
YDFL
EOMLock-In
Amplifier
X & YSignal
Lock-In Amplifier
X & YSignal
Wave-meter
40 kHzPlasma
Frequency
80 MHz1 × Cavity Free Spectral Range
90o Phase Shift
IPS
2f
ni = np - ns
Freq. CombAOM
K. N. Crabtree, et al. Chem. Phys. Lett. (2012), 551, 1-6.
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Comb Calibration
Wave-meter
Freq. CombAOM
[…]
Signal Pump
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Comb Calibration
Wave-meter
Freq. CombAOM
[…]
Signal Pump
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Comb Calibration
Wave-meter
Freq. CombAOM
[…]
Signal PumpSignal
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H3+ Spectra
Sig
nal
Signal
Doubly Degenerate n2 Band
H3+ Transition Notation
𝐺≡|𝑘− 𝑙|{𝑃∨𝑄∨𝑅 }( 𝐽 ,𝐺){𝑢∨𝑙 }
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Lamb Dips & Saturation• High Power Optical Saturation Lamb dips• Second Comb Calibrated Observation of Lamb dips
• In NICE-OHVMS fm-triplet causes many Lamb dips
H.-C. Chen et al. Phys. Rev. Lett. (2012), 109, 263002.K.N. Crabtree et al. Chem. Phys. Lett. (2012), 551, 1.
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Lamb Dips & Saturation• High Power Optical Saturation Lamb dips• Second Comb Calibrated Observation of Lamb dips
• In NICE-OHVMS fm-triplet causes many Lamb dips
H.-C. Chen et al. Phys. Rev. Lett. (2012), 109, 263002.K.N. Crabtree et al. Chem. Phys. Lett. (2012), 551, 1.
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Lamb Dips & Saturation• High Power Optical Saturation Lamb dips• Second Comb Calibrated Observation of Lamb dips
• In NICE-OHVMS fm-triplet causes many Lamb dips
H.-C. Chen et al. Phys. Rev. Lett. (2012), 109, 263002.K.N. Crabtree et al. Chem. Phys. Lett. (2012), 551, 1.
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Lamb Dips & Saturation• High Power Optical Saturation Lamb dips• Second Comb Calibrated Observation of Lamb dips
• In NICE-OHVMS fm-triplet causes many Lamb dips
H.-C. Chen et al. Phys. Rev. Lett. (2012), 109, 263002.K.N. Crabtree et al. Chem. Phys. Lett. (2012), 551, 1.
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Lamb Dips and Fits
R(2,2)l Transition
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Transition Frequencies
𝜎 𝜇=𝜎√𝑛
St. Err. = St. Dev. Of Mean
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Lamb Dip Signal-to-Noise-RatioLamb Dip SNR:
𝑆𝑁𝑅=𝑆𝑖𝑔𝑛𝑎𝑙𝑝𝑘−𝑝𝑘𝜎𝑟𝑒𝑠𝑖𝑑𝑢𝑎𝑙𝑠
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Lamb Dip Signal-to-Noise-Ratio
R(1,0)R(3,2)l
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Frequency Calibration Test
• First use of a comb with this instrument• Need to ensure proper calibration• Lamb dips of methane
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Instrumental Layout
OPO
YDFL
EOMLock-In
Amplifier
X & YSignal
Lock-In Amplifier
X & YSignal
Wave-meter
40 kHzPlasma
Frequency
80 MHz1 × Cavity Free Spectral Range
90o Phase Shift
IPS
2f
ni = np - ns
Freq. CombAOM
1.4 kHzModulationFrequency
3f
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Frequency Calibration Test
• First use of a comb with this instrument• Need to ensure proper calibration• Lamb dips of methane• Acquired Lamb dips for F1
(2) component of P(7) transition of n3 band
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Frequency Calibration Test
Lamb dip of methaneFit with 2nd derivative of Lorentzian
5 kHz diff. from Takahata et al. ~30 kHz st. dev. from fit
K. Takahata et al. Phys. Rev. A. (2009) 80, 032518.
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ConclusionsComb calibrated H3
+ transitions reported
Higher S/N lines have sub-MHz precision
Methane used to validate comb calibration
Values differ than Chen et al. H.-C. Chen et al. Phys. Rev. Lett. (2012), 109, 263002.
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Acknowledgements
Springborn FellowshipNSF GRF (DGE 11-44245 FLLW)