State-to-state rotational energy transfer and reaction with ketene of highly vibrationally excited [ital [tilde b]] [sup 1][ital B][sub 1] CH[sub 2] by time-resolved Fourier transform emission spectroscopy

Journal Article · Sat May 01 00:00:00 EDT 1993 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.464780· OSTI ID:6585436

Hartland, G V; Qin, D; Dai, H ^[1]

---

1. Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323 (United States)

Dispersed fluorescence spectra from the CH[sub 2] [ital [tilde b]] [sup 1][ital B][sub 1][r arrow][ital [tilde a]] [sup 1][ital A][sub 1] band were recorded with time-resolution by Fourier transform emission spectroscopy after pulsed excitation of a single rotational level of the [ital [tilde b]] [sup 1][ital B][sub 1] (0,16[sup 0],0) state. Fluorescence observed from the initially excited level and from levels populated by rotational energy changing collisions with the bath gas (ketene) was used to deduce the state-to-state rate constants for rotational energy transfer and the state-resolved rate constants for total collisional removal of [ital [tilde b]] [sup 1][ital B][sub 1] CH[sub 2]. The observed propensity rules for rotational energy transfer---[Delta][ital J]=[plus minus]2, [Delta][ital K][sub [ital a]]=0, and [Delta][ital K][sub [ital c]]=[plus minus]2---are consistent with a quadrupole--dipole interaction between [ital [tilde b]] [sup 1][ital B][sub 1] (0,16[sup 0],0) CH[sub 2] and ketene. The existence of a quadrupole in the intermolecular interaction suggests that the structure of CH[sub 2] in the [ital [tilde b]] [sup 1][ital B][sub 1] (0,16[sup 0],0) state, averaged over the time of a collision, must be linear. The state-to-state rotational energy transfer rate constants range from approximately equal to the hard sphere gas kinetic rate to four times the gas kinetic rate, with the largest rate constants between rotational levels with the smallest energy gaps. Examination of fluorescence spectra recorded with polarization analysis shows that rotationally elastic ([Delta][ital J]=0)[ital M] changing collisions are negligible.

• DOE Contract Number: FG02-86ER13584
• OSTI ID: 6585436
• Journal Information: Journal of Chemical Physics; (United States), Vol. 98:9; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
KETENES
ENERGY TRANSFER
CHEMICAL REACTIONS
EMISSION SPECTRA
EXCITED STATES
FOURIER TRANSFORM SPECTROMETERS
ROTATIONAL STATES
TIME RESOLUTION
VIBRATIONAL STATES
ENERGY LEVELS
MEASURING INSTRUMENTS
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
RESOLUTION
SPECTRA
SPECTROMETERS
TIMING PROPERTIES
664300* - Atomic & Molecular Physics- Collision Phenomena- (1992-)