K_2(~1∧_g)高位态的预解离和碰撞转移

Predissociation and collisional transfer of the high-lying of the K_2(~1∧_g)

利用光学双共振和激光光谱技术,测量了K_2(~1A_g)态的预解离率和碰撞转移率.脉冲激光将K_2(1~1∑_g^+)基态激发至1~1∑_u^+态,由连续激光激发1~1∑_u^+至激高位~1A_g态.在不同K密度下,记录~1A_g→~1A_u跃迁的时间分辨荧光,光强的对数与衰变时间成线性关系,从直线的斜率得到~1A_g态的有效寿命,由Stern-Volmer方程得到~1A_g态的辐射率与预解离率之和及总的碰撞去布居截面.在不同的K密度下测量时间积分荧光强度I_3[K_2(~1A_g)→K_2(~1A_u)],I_2[K(6S)→K(4P_(3/2))]和I_1[K(4D)→K(4P_(3/2))],光强比I_1/I_3和I_2/I_3与K密度也成线性关系.从直线的斜率和截距并结合从Stern-Volmer方程得到的结果,确定K_3(~1A_g)的预解离率Γ_(P6S)=(1.2±0.4)×10~7s^(-1),Γ_(P4D)=(0.8±0.3)×10~7s^(-1)和碰撞转移截面σss=(1.9±0.6)×10^(-14)cm^2,σ_(4D)=(9.0±3.0)×10^(-15)cm^2.

The high-lying ^1∧g state of K2 is excited by using optical-optical double resonance spectroscopy technique. The predissociative rates and collissonal transfer rates of K2（^1∧g） states are experimentally measured. A pulse laser was used to pump K2 from ground state 1^1∑g^＋ to the intermediate 1^1∑u^＋ state. Then a cw laser was used to excite high-lying ^1∧g state. Predissociative state radiative process was monitored by time-resolved fluorescence from the upper 1As state to lower rovibrational level of the ^1∧u state. From time-resolved fluorescence for the ^1∧g→^1∧u transition at different K densities, the semilog plots were shown. The slopes yielded the effective lifetimes of the ^1∧g state. Based on the Stern-Volmer equation, the sum of the radiative and predissociative rates and the total cross section for deactivation of the K2 （^1∧g） have been determined means of collision with K is （5.6 ±1.1）× 10^-14 cm62. At different K density, the time-integrated intensities of I3[K2（^1∧g）→K2（^1∧u）],I2[K（6S）→K（4P3/2）] and I1[K（4D）→K（4P3/2）] were measured . The rations I1/I3 and I2/I3 versus the K densities can be fitted by the straight lines. By combining the slope and the intercept with the result obtained by the Stern-Volmer equation we obtain predissociative rates, ГP6S=（1.2±0.4）×10^7s^-1 ,ГP4D=（0.8±0.3）×10^7s^-1 and collisional transfer cross sections σ6S=（1.9±0.6）×10^-14cm^2,σ4D=（9.0±3.0）×10^15cm^2.