碰撞诱导振动能量转移K_2[1~1Σ_u^+(v′=2)]+He,H_2→K2[1~1Σ_u^+(v′=1,3)]+He,H_2

Collision-Induced Vibrational Energy Transfer: K_2[1~1Σ_u^+(v′=2)]+He,H_2→K2[1~1Σ_u^+(v′=1,3)]+He,H_2

在样品池条件下,利用激光诱导荧光方法研究了K2[11Σ+u(v′=2)]+He,H2→K2[11Σ+u(v′=1,3)]+He,H2的碰撞能量转移。池温保持在420 K,He和H2气压在40~250 Pa之间变化。脉冲激光激发K2基态至11Σ+u(v′=2)态,荧光中含有直接和碰撞转移荧光成分,记录直接11Σ+u(v′=2)→11Σ+g(v″=0)荧光发射的时间分辨强度。在发射开始时v′=2能级的布居未受v′=1,3→v′=2碰撞转移的影响,因此光强为一纯指数曲线,从强度的对数值给出的直线斜率得到有效寿命,由Stern-Volmer方程得到v′=2→v″=0的辐射寿命为(36±7)ns,v′=2与He和H2碰撞的总的转移截面分别为(3.0±0.5)×10-16cm2和(6.4±1.2)×10-15cm2。在不同的He和H2气压下,测量v′=1,2,3→v″=0的时间积分荧光强度,结合11Σ+u(v′=1,3)能量辐射率的测量,得到了v′=2→v′=1和v′=2→v′=3的碰撞转移面分别为(1.4±0.5)×10-16cm2,(1.2±0.4)×10-16cm2(对K2+He)和(3.2±1.0)×10-15cm2,(2.6±0.9)×10-15cm2(对K2+H2)。

Collisional energy transfer processes K2[11Σ＋u（v′=2）]＋He,H2→K2[11Σ＋u（v′=1,3）]＋He,H2 were studied by laser induced fluorescence under gas cell conditions.During the experiments,the cell temperature was kept constant at 420K.The buffer gas pressure was varied over the range from 40 to 250 Pa,K2 molecules were irradiated with pulses of radiation from an OPO laser,populating K2[11Σ＋u（v′=2）] by photon absorption.The resulting fluorescence included the direct component emitted in the decay of the optically excited state and the sensitized components arising from collisionally populated states.The decay signal of time-resolved fluorescence from 11Σ＋u（v′=2）→11Σ＋g（v″=0） transition was monitored.In the early period after excitation,only very little population in states v′=1 or 3 had yet accumulated,the rate of collisional activation to the state v′=2 was negligible.The decay curve of the v′=2→v″=0 was treated as a single exponential function.From the measurement of the time-resolved fluorescence,the semilog plot was shown.The slope yielded the effective lifetime of the v′=2→v″=0 transition.Based on the Stern-Volmer equation,the radiative lifetime（36±7） ns was obtained.The total cross sections for deactivation of 11Σ＋u（v′=2） state by means of collisions with He and H2 are（3.0±0.5）×10-16 cm2 and（6.4±1.2）×10-15 cm2,respectively.The radiative lifetimes of 11Σ＋u（v′=1,3） states can also be determined through time-resolved fluorescence in pure K vapor.The time-integrated intensities of 11Σ＋u（v′=1,2,3）→11Σ＋g（v″=0） transition at different He or H2 pressure were measured.The ratio of fluorescence intensities versus 1/P（He,H2） can be fitted by a straight line.The slopes yield the cross sections σ（v′=2→v′=1）=（1.4±0.5）×10-16 cm2 and（3.2±1.0）×10-15 cm2;σ（v′=2→v′=3）=（1.2±0.4）×10-16 cm2 and（2.6±0.9）×10-15 cm2 for He and H2,respectively.Cross sections for the effective quenching of the v′=1,2,3 states were also determined.To our knowledge,the cross-sections for these processes are reported for first time.