| The strong electric fields produced by focused pulses of ultrafast optical lasers can spatially align molecules at moderate intensities or ionize atoms and molecules at higher intensities. Tunable, polarized, microfocused x-ray pulses at the Advanced Photon Source have been used to record x-ray absorption spectra of atoms and molecules in strong laser fields. Notable advantages of tunable x-ray absorption include atomic specificity, high penetration through dense targets, ultrafast response by emission of x-ray fluorescence, and the sensitivity of resonant absorption to alignment of the laser-excited atomic or molecular target. Examples will be presented from experiments on laser-ionized Kr and BrCF3 and laser-aligned BrCF3. Future opportunities using short-pulse synchrotron x-rays will also be discussed. |
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