Tuthill Daniel R, Scarborough Timothy D, Gorman Timothy T, Hamer Kyle A, Jones Robert R, Gaarde Mette B, Lopata Kenneth, Mauger François, Schafer Kenneth J, DiMauro Louis F
Department of Physics, The Ohio State University, Columbus, Ohio43210, United States.
Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana70803, United States.
J Phys Chem A. 2022 Nov 24;126(46):8588-8595. doi: 10.1021/acs.jpca.2c04606. Epub 2022 Nov 10.
We present molecular-frame high-harmonic spectroscopic measurements of the spectral intensity and group delay of carbon dioxide. Using four different driving wavelengths and a range of intensities at each wavelength for high-harmonic generation, we observe a well-characterized minimum in the harmonic emission that exhibits both a wavelength and intensity dependence. Using the intensity dependence at each driving wavelength, we classify the minimum as due to either a structural two-center interference or dynamic multichannel interference, consistent with previous literature. By additionally measuring the group delay at each driving wavelength and intensity, we find that the sign of the group delay excursion across the interference is an acute probe of the interference mechanism. The experimental results are confirmed by ab initio time-dependent density functional theory calculations of both the spectral intensity and the phase of the harmonic emission.
我们展示了二氧化碳光谱强度和群延迟的分子框架高谐波光谱测量结果。利用四个不同的驱动波长以及每个波长下一系列用于高谐波产生的强度，我们观察到谐波发射中一个特征明显的最小值，该最小值呈现出波长和强度依赖性。利用每个驱动波长下的强度依赖性，我们将该最小值归类为结构双中心干涉或动态多通道干涉所致，这与先前的文献一致。通过额外测量每个驱动波长和强度下的群延迟，我们发现干涉过程中群延迟偏移的符号是干涉机制的敏锐探针。光谱强度和谐波发射相位的从头算含时密度泛函理论计算证实了实验结果。
