Picosecond studies of the temperature dependence of homogeneous and inhomogeneous vibrational linewidth broadening in liquid acetonitrile

Journal Article · Sun Jan 01 04:00:00 EST 1984 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.446410· OSTI ID:5389035

George, S M; Harris, A L; Berg, M; Harris, C B

The temperature dependence of homogeneous and inhomogeneous vibrational linewidth broadening is reported for the symmetric CH/sub 3/-stretching vibration in acetonitrile over its entire liquid range at P = 1 atm. A selective excite-and-probe vibrational dephasing experiment based on transient stimulated Raman scattering in high laser depletion is used to measure the homogeneous dephasing times T/sub 2/. The separation of homogeneous and inhomogeneous broadening processes is accomplished using the combined results of isotropic spontaneous Raman studies and selective picosecond vibrational dephasing experiments. As a function of temperature, the relative contributions of homogeneous and inhomogeneous broadening are shown to change significantly in opposing directions. Agreement between experiment and theory supports previous suggestions that homogeneous broadening is caused by rapidly varying processes which affect the vibration via short range repulsive forces. The results also suggest that inhomogeneous broadening is caused by slowly varying local density sites which interact with the vibration through long range attractive forces.

• Research Organization: Department of Chemistry and Materials and Molecular Research Division of Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720
• OSTI ID: 5389035
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 80:1; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640300* -- Atomic
Molecular & Chemical Physics
74 ATOMIC AND MOLECULAR PHYSICS
ENERGY LEVELS
EXCITED STATES
FLUIDS
LINE BROADENING
LINE WIDTHS
LIQUIDS
NITRILES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
RAMAN SPECTRA
SPECTRA
TEMPERATURE DEPENDENCE
VIBRATIONAL STATES