The HCO [tilde B][sup 2]A[prime] [leftrightarrow] [tilde X][sup 2]A[prime] system: Fluorescence excitation and stimulated emission pumping spectra

Journal Article · Thu Jul 01 04:00:00 EDT 1993 · Journal of Nondestructive Evaluation; (United States)

OSTI ID:6074246

Adamson, G W; Zhao, Xinsheng; Field, R W ^[1]

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1. Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Chemistry

The 0[sup 0][sub 0] band of the HCO [tilde B][sup 2] A[prime] [leftrightarrow] [tilde X][sup 2]A[prime] system, observed at 0.06 cm[sup [minus]1] resolution in a [approximately]300K fluorescence excitation spectrum, is rotationally analyzed. Rotational congestion combined with irregularity of the K[prime][sub a], K[prime][sub a] + 1 intervals, prevented definitive assignments for K[prime][sub a] > 2 levels. A vibronic level at t[sub 0] = 41,284 cm[sup [minus]1], previously assigned as the zero-point level of a [tilde C][sup 2] A[double prime]' electronic state, is conclusively shown by its hybrid a, b-type rotational contour to be the [tilde B][sup 2]A[prime] (1, 0, 0) level. From the relative intensities of a-type and b-type rotational transitions, the [tilde B][sup 2] A[prime]-[tilde X][sup 2] A[prime] 0[sub 0][sup 0] band electric dipole transition moment is found to lie (in the plane of the HCO molecule) at an angle of 31(4)[degree] relative to the a-inertial axis. Stimulated emission pumping (SEP) spectra (0.06 cm[sup [minus]1] resolution) of two [tilde X][sup 2] A[prime]-state vibrational resonances, ([nu][sub CH], [nu][sub CO], [nu][sub BEND]) = (0, 5, 0) and (0, 4, 1) located at T[sub [nu]] = 9,091.97(3) and 8,478(1) cm[sup [minus]1], respectively, both lying well above the H-CO dissociation limit, exhibited typical asymmetric top rotational structure and highly vibrational mode specific linewidths. Despite the lower energy of the (0, 4, 1) level, its much larger linewidth than that of (0, 5, 0) implies that the bending vibration ([nu][sub 3][double prime]) is much more effective than the CO stretch ([nu][sub 2][double prime]) in promoting dissociation.

• DOE Contract Number: FG02-87ER13671
• OSTI ID: 6074246
• Journal Information: Journal of Nondestructive Evaluation; (United States), Journal Name: Journal of Nondestructive Evaluation; (United States) Vol. 160:1; ISSN 0195-9298; ISSN JNOED5
• Country of Publication: United States
• Language: English

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DATA ANALYSIS
DIPOLE MOMENTS
DISSOCIATION
E1-TRANSITIONS
EARTH ATMOSPHERE
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