文献类型：期刊文献

英文题名：Excitation Transfer between High-Lying States in K₂ in Collisions with Ground State K and H₂ Molecules

作者：Shen Xiao-yan[2];Liu Jing[1];Dai Kang[1];Shen Yi-fan[1]

机构：[1]Xinjiang Univ, Sch Phys Sci & Tech, Urumqi 830046, Peoples R China;[2]E China Univ Sci & Technol, Sch Chem & Mol Engn, Shanghai 200237, Peoples R China

年份：2010

卷号：30

期号：2

起止页码：289

外文期刊名：SPECTROSCOPY AND SPECTRAL ANALYSIS

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000274321800001)】；

语种：英文

外文关键词：Laser spectroscopy; Energy transfer; Time-resolved fluorescence; Cross section; K-2; H-2

摘要：Pure potassium vapor or K-H-2 mixture was irradiated in a glass fluorescence cell with pulses of 710 nm radiation from an OPO laser, populating K-2((1)Lambda(g)) state by two-photon absorption. Cross sections for (1)Lambda(g)-(3)Lambda(g) transfer in K-2 were determined using methods of molecular fluorescence. During the experiments with pure K vapor, the cell temperature was varied between 553 and 603 K. The K number density was determined spectroscopically by the white-light absorption measurement in the blue wing of the self-broadened resonance D-2 line. The resulting fluorescence included a direct component emitted in the decay of the optically excitation and a sensitized component arising from the collisionally populated state. The decay signal of time-resolved fluorescence from (1)Lambda(g)-> 1 (1)Sigma(+)(u) transition was monitored. It was seen that just after the laser pulse the fluorescence of the photo-excited level decreased exponentially. The effective lifetimes of the (1)Lambda(g) state can be resolved. The plot of reciprocal of effective lifetimes of the (1)Lambda(g) state against K densities yielded the slope that indicated the total cross section for deactivation and the intercept that provided the radiative lifetime of the state. The radiative lifetime (20+/-2) ns was obtained. The cross section for deactivation of the K-2((1)Lambda(g)) molecules by collisions with K is (2. 5+/-0. 3) X 10(-14) cm(2). The time-resolved intensities of the K-2((3)Lambda(g))-> 1 (3)Sigma(+)(u)(484 nm) line were measured. The radiative lifetime (16. 0+/-3. 2) ns and the total cross section (2. 5+/-0. 6) X 10-(14) cm(2) for deactivation of the K-2((3)Lambda(g)) state can also be determined through the analogous procedure. The time-integrated intensities of (1)Lambda(g)-> 1 (1)Sigma(+)(u) and (3)Lambda(g)-> 1 (3)Sigma(+)(u) transitions were measured. The cross section (1. 1+/-0. 3) X 10(-14) cm(2) was obtained for K-2((1)Lambda(g)) + K -> K-2((3)Lambda(g)) + K collisions. During the experiments with K-H-2 mixture, the cell temperature was kept constant at 553 K. The H-2 pressure was varied between 40 and 400 Pa. The effects of K-2-K collisions could not be neglected. These effects were subtracted out using the results of the pure K experiments. The cross section (2. 7+/-1. 1) X 10(-15) cm(2) was obtained for K-2((1)Lambda(g)) + H-2 -> K-2((3)Lambda(g)) + H-2 collisions. The cross section is (6. 8+/-2. 7) X 10(-15) cm(2) for K-2((3)Lambda(g)) + H-2 -> states out of K-2((3)Lambda(g)) + H-2 collisions.