Infrared Multiple Photon Absorption of Silicon Tetra‐Fluoride and Anisole

Abstract

AbstractThe infrared multiple absorption probabilities of the title molecules are measured at two frequency ranges: one for which the single photon absorption (SPA) cross section is large (range I), and another for which it is much smaller (range II). For SiF4, the high power absorption probability in range I is much smaller than the SPA cross section. Collisions significantly increase the average number of photons absorbed. In range II, the absorption cross section increases upon increasing the laser fluence. For anisole, the same fluence effect is qualitatively observed, but it is less pronounced in range I. For anisole pressure exceeding 0.1 torr collisions with argon do not change the average number of photons absorbed per molecule. The 10.2 μ absorption in SiF4 is suggested to be initiated by a single photon hot band absorption, followed by absorption in the quasi‐continuum (QC). QC absorption cross sections are in the range of (5–20) × 10−21 cm2 for both SiF4 and anisole.