Two-photon excitation cross section of the B ← X(0,0) band of CO measured by direct absorption
Two-photon excitation cross section of the B ← X(0,0) band of CO measured by direct absorption
复制标题
通过直接吸收测量的 CO B ← X(0,0) 带的双光子激发截面
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
R. Farrow
中科院分区：
文献类型：
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作者：
M. Rosa;R. Farrow
我们报告了 CO B←X(0, 0) 波段中双光子吸收率的新测量结果，这是根据充分表征的空间轮廓的傅里叶变换限制脉冲获得的吸收光谱确定的。通过将 230 nm 附近的 CO Q 分支的测量吸收光谱与脉冲衰减的非线性模型进行比较，我们得出了光谱积分截面 σ0(2)。空间和时间相关模型考虑了双光子吸收和激发态的单光子光电离。 Q 分支光谱轮廓是用先前测量的碰撞展宽和偏移系数来模拟的。值得注意的是，对于焦点处 80-350 MW/cm2 的适度辐照度，在 12-33 kPa 压力下单次通过纯 CO 时，观察到 Q 分支峰值衰减 10% 或更大。我们的光谱积分截面结果（五次实验的平均值）为 σ0(2)=(1.5+0.7/-0.2)×10-35 cm4。
We report new measurements of the two-photon absorption rate in the B←X(0, 0) band of CO, as determined from absorption spectra obtained with Fourier-transform-limited pulses of well-characterized spatial profile. By comparing measured absorption spectra of the CO Q branch near 230 nm with a nonlinear model for the pulse attenuation, we derive the spectrally integrated cross section σ0(2). The space- and time-dependent model considers two-photon absorption followed by one-photon photoionization of the excited state. The Q-branch spectral profile is simulated with previously measured coefficients of collisional broadening and shift. Remarkably, for modest irradiances of 80–350 MW/cm2 at the focus, attenuations of 10% and greater at the Q-branch peak were observed in a single pass through neat CO at pressures of 12–33 kPa. Our result for the spectrally integrated cross section, averaged over five experiments, is σ0(2)=(1.5+0.7/-0.2)×10-35 cm4.