Na(3P)+Na(3P)→Na(4F)+Na(3S)碰撞激发能量转移截面

CROSS SECTION FOR COLLISIONAL EXCITATION ENERGY TRANSFER IN Na(3P) + Na(3P)→Na(4F) + Na(3S)

利用激光(调离NaD_2线±20GHz)激发钠蒸汽,测量Na(3P)+Na(3P)→Na(4F)+Na(3S)的碰撞激发转移截面。因4F→3D的荧光位于红外(1.84μm),故检测3~2D_(3/2)→3~2P_(1/2)(818.3nm)和3~2D→3~2P_(3/2)(819.5nm)级联荧光信号。通过测量激光频率的Rayleigh散射光,直接D_2线荧光和敏化D_1线荧光分布,确定了钠原子密度,定出了有效辐射俘获衰变率Γ_(D_1)~e,Γ_(D_2)~e。结合激光功率吸收率的测量得到了Na(3P)的密度,从而给出转移截面σ(4F)=37A^2(±33％)。与其他作者的实验结果和理论值作了比较,进行了讨论。

Sodium vapor was excited by a cw dye laser, tuned±20GHz from the D2 resonance line. Cross section for the excitation transfer process Na(3P) + Na (3P)→Na(4F) + Na(3S) was measured. Since the direct 4F→3D fluorescence could not be detected with our apparatus, we monitored instead the cascade 32D→32P fluorescence. The spatial distributions of the Rayleigh compenent at the laser freguency,D2 and D1 fluorescence emissions were measured. Combined with a measurement of absorption coefficient, the sodium density was yielded. Trapped effective radiation decay rate could be determined. The excited-atom density was measured by the power absorbed. Our result was σ4F=37A2(±33%).Comparison of our result with other experiments and theory was made.