69 th international symposium on molecular spectroscopy consistent assignment of the vibrations of...
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69th International Symposiumon Molecular Spectroscopy
Consistent Assignment of the Vibrations of
Monohalosubstituted BenzenesJoe P. Harris, Anna Andrejeva, William D. Tuttle, Timothy G.
WrightSchool of Chemistry, University of Nottingham, UKIgor Pugliesi, Christian Schriever
Fakultät für Physik, Ludwig-Maximilians-Universität, München
Notation schemes for substituted benzenes
Introduction - Existing schemes
M notation - Mass trends - G-W Notation
Experiments
- Previous studies - Fluorobenzene - Fluorobenzene-d5
Conclusions - Future work
• Wilson notation
• Mulliken
notation• Varsányi notation
• Normal modes of molecule labelled with respect to normal modes of benzene
• Benzene has D6h symmetry; lowers to C2v upon substitution
• Normal modes arranged in symmetry blocks, then by decreasing energy
• Does not account for energetic re-ordering
• Loses information on motion of vibrations
• Subdivides substituents into two classes;‘heavy’ and ‘light’
• Unclear division between the two classes
Gardner-Wright Notation
• Takes fluorobenzene as a template molecule
• Applies Mulliken labelling scheme(ie. decreasing energy ordering within symmetry blocks)
• Treats the target molecule’s substituent as a point mass
J Chem Phys 135 114305 (2011)
Introduction - Existing schemes
M notation - Mass trends - G-W Notation
Experiments
- Previous studies - Fluorobenzene - Fluorobenzene-d5
Conclusions - Future work
Mass Trends Introduction - Existing schemes
M notation - Mass trends - G-W Notation
Experiments
- Previous studies - Fluorobenzene - Fluorobenzene-d5
Conclusions - Future work
J Chem Phys 135 114305 (2011)
Some mode switching seen for lower masses
Mass trends settle down quite quickly
Lowest mass atomic substituent would be fluorine
x = 1 - 20
Gardner-Wright Notation
• Takes fluorobenzene as a template molecule
• Applies Mulliken labelling scheme(ie. decreasing energy ordering within symmetry blocks)
• Treats the target molecule’s substituent as a point mass
J Chem Phys 135 114305 (2011)
Introduction - Existing schemes
M notation - Mass trends - G-W Notation
Experiments
- Previous studies - Fluorobenzene - Fluorobenzene-d5
Conclusions - Future work
• Uses Duschinsky mixing approach to show correlation between normal modes in different molecules
• Produces a Duschinsky matrix
Gardner-Wright Notation Introduction - Existing schemes
M notation - Mass trends - G-W Notation
Experiments
- Previous studies - Fluorobenzene - Fluorobenzene-d5
Conclusions - Future work
M18 and M19 mix heavily upon excitation
‘True’ Duschinsky Mixing
GeneralisedDuschinsky Mixing
Previous Studies• Lipp and Seliskar (1981)
J. Mol. Spec., 87, 242 (1981)
Vapour-phase absorptionFC6H5 and FC6D5
• Butler, Moss, Yin, Schmidt,and Kable (2007)J. Chem. Phys., 127, 094303 (2007)
Laser induced fluorescence and dispersed fluorescence
More than 40 DF spectra
• Pugliesi, Tonge, and Cockett (2008)J. Chem. Phys., 129, 104303 (2008)
RICC(2) frequency calculationsZEKE spectroscopy
Introduction - Existing schemes
M notation - Mass trends - G-W Notation
Experiments
- Previous studies - Fluorobenzene - Fluorobenzene-d5
Conclusions - Future work
Fluorobenzene-h5
Introduction - Existing schemes
M notation - Mass trends - G-W Notation
Experiments
- Previous studies - Fluorobenzene - Fluorobenzene-d5
Conclusions - Future work
(1 + 1) REMPI
Fluorobenzene-d5 and -h5
Introduction - Existing schemes
M notation - Mass trends - G-W Notation
Experiments
- Previous studies - Fluorobenzene - Fluorobenzene-d5
Conclusions - Future work
Fluorobenzene-h5
Fluorobenzene-d5
Fluorobenzene-d5
Introduction - Existing schemes
M notation - Mass trends - G-W Notation
Experiments
- Previous studies - Fluorobenzene - Fluorobenzene-d5
Conclusions - Future work
Observedposition /
cm-1
PotentialAssignme
nts
789.0
M8
M143M18
M16M18
M13M19
801.2M14M18M30
M192
809.8 M15M20
837.4
M14M20M29
M27
M13M17
M14M182M20
850.4M7
M17M19
M142M29
Observedposition /
cm-1
PotentialAssignme
nts
701.4702.6705.0
M16M20
M143M20
M17M18
708.8 M14M20M30
717.0718.2
M10
M14M16
M144
Observedposition /
cm-1
PotentialAssignments
917.0
M13M16
M18M20M29
M13M20M30
M13M143
928.0929.0929.6931.0933.6934.8
M142M19M20
M17M203
M19M20M30
M13M14M30
M14M18M29
M9
M12M17
M14M183
957.4M14M19M30
M13M18M202
Conclusions Introduction - Existing schemes
M notation - Mass trends - G-W Notation
Experiments
- Previous studies - Fluorobenzene - Fluorobenzene-d5
Conclusions - Future work
Future Work
• Record 2D-LIF spectra of fluorobenzene
• Possibility of time-resolved study
• Show usefulness of scheme when applied to other monosubstituted benzenes - coming up next!
Introduction - Existing schemes
M notation - Mass trends - G-W Notation
Experiments
- Previous studies - Fluorobenzene - Fluorobenzene-d5
Conclusions - Future Work
Acknowledgements
Prof. Timothy G. Wright
Anna Andrejeva
William Tuttle
Igor Pugliesi
Christian Schriever
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