Na<sub>2</sub>高振动态与CO<sub>2</sub>间碰撞转移概率分布的实验测量

doi:10.3964/j.issn.1000-0593(2023)06-1760-05

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Abstract The full state-resolved distribution of scattered CO₂(00⁰0) molecules from collisions with highly vibrationally excited Na₂(ν″=30 and 45) is reported and investigated how internal energy content impacts the dynamics for collisional quenching of high energy molecules. Stimulated emission pumping was used to excite the Na₂(ν″=30, J=11) and Na₂(ν″=45, J=11). Under single-collision conditions, rotational levels of the vibrationally relaxed Na₂(ν″-1) and Na₂(ν″-2) are identified. Levels attributable to upward vibrational transfer could not be observed. The change in Na₂ rotational energy was determined. Quantifying the simultaneous population change for low J states is accomplished by transient line profile measurements for individual states. The line width is a measure of the translational energy spread of the scattered molecules and the area under the line profile is a measure of the J-specific population. The nascent translational temperature T_pres (for presence) and T_dep (for depletion) are determined from the measured line widths Δν_presand Δν_dep, respectively. The presence line widths Δν_pres were obtained by fitting the double-Gaussian function to the transient line profile data at t=1 μs. The lab-frame translational temperature T_pres for the presence of scattered CO₂ molecules and the relative (center-of-mass frame) translational temperatures T_rel for Na₂(ν″) /CO₂ collisions were determined based on Δν_pres measurements. Average translational energy gains for the presence of CO₂(00⁰0, J) following collisions with vibrationally excited Na₂ are determined using 〈E_rel〉=3/2k(T_rel-T_cell). The comparison shows that the Na₂ vibrational energy that goes into the translational energy of the CO₂ strongly depends on the initial energy: the translational energy of the J-specific collision pruducts increases by 56% or more for a 35% increase in donor vibrational energy. The appearance rate constants for individual CO₂ rotational states are determined. The total appearance rate constant for Na₂(ν″=30) is k_app=(6.6±1.5)×10^-10 cm³·molecule^-1·s^-1. This result is comparable to that for Na₂(ν″=45), where the appearance rate constant is k_app=(5.9±1.3)×10^-10 cm³·molecule^-1·s^-1. The results show that the Na₂(ν″)/CO₂ collision frequency is not particularly sensitive to the amount of Na₂(ν″) vibrational energy. The full energy transfer distributions P(ΔE) for product energy gain confirm that the ΔE distributions broaden rapidly for relatively small increases in donor energy for Na₂(ν″)/CO₂ collisions. P(ΔE) curves for Na₂(ν″=30) are shifted to lower ΔE values compared to Na₂(ν″=45) data. The ΔE values in P(ΔE) include the change in CO₂ rotational energy and the change in translational energy of Na₂(ν″) and CO₂ plus the change in rotational energy of Na₂(ν″). Numerical integration of P(ΔE) over the full range of ΔE yields 〈ΔE〉_trans=590 cm^-1; in comparison, 〈ΔE〉_trans=880 cm^-1 for Na₂(ν″=45).

Key words：Collisional energy transfer; Laser induced fluorescence; Transient line profile; Rate contant; Energy gain distribution function; High vibrationally excited Na₂; CO₂

Received: 2022-03-22 Accepted: 2022-10-31

ZTFLH:

O561.5

Corresponding Authors: WANG Shu-ying E-mail: wsy-smile@163.com

Cite this article:

WANG Shu-ying,YOU De-chang,MA Wen-jia, et al. Experimental Collisional Energy Transfer Distributions for Collisions of CO₂ With Highly Vibrationally Excited Na₂[J]. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2023, 43(06): 1760-1764.

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https://www.gpxygpfx.com/EN/10.3964/j.issn.1000-0593(2023)06-1760-05 OR https://www.gpxygpfx.com/EN/Y2023/V43/I06/1760