ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
The technique of anharmonic forced Rayleigh scattering is developed and applied to the study of saturated absorption in liquids. Isobaric heating following saturated absorption at a crossed beam interference pattern creates an anharmonic transient thermal grating containing harmonics of the single spatial frequency present in the intensity. Diffraction observed for a probe beam incident at the Bragg angle for the second harmonic grating component provides a zero-background measurement of a deviation from linear absorption. Gaussian spatial and temporal beam profiles are taken into account and the angular sensitivity of the grating is measured and compared with theory. Transient decay rates are also measured and found to be in good agreement with the theory. A four-level saturation model is developed, and the saturation parameter Isat is related to kinetic parameters for the two dominant causes of saturation in liquids: intermediate state "bottlenecking'' and photochemical change. The lack of second order diffraction from azulene in CCl4 allows us to put limits on the saturation intensity, photochemical yield, excited state cross section, and two-photon cross section of this molecule. The relative diffraction efficiency and dependence on excitation intensity of two diffraction orders are used to determine the nonrecombinant dissociation yields of I2 (excited at 532 nm) in hexadecane and hexane. The dissociation yields are 0.038 and 0.153, respectively.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.452107
