Probe Laser Wavelength Research Articles

Time-resolved resonance Raman spectroscopy of the radical anion of disodium anthraquinone-2,6-disulphonate

Time-resolved resonance Raman spectra of anthraquinone-2,6-disulphonate (AQ26DS) in oxygenated aqueous solution in the presence of nitrite ion have been obtained. AQ26DS was pumped into the excited singlet state by 337 nm laser excitation and the time evolution of the spectrum observed at a probe laser wavelength of 480 nm. An analysis of the kinetics indicates that the transient spectrum is due to the radical anion of AQ26DS.

Vibrational energy redistribution in glyoxal following internal conversion

The vibrational redistribution of energy following internal conversion in glyoxal has been studied in a molecular beam using the ’’pump-and-probe’’ technique. A beam of glyoxal is initially pumped from So to a selected vibronic level of S1. After internal conversion occurs, a tunable dye laser is used to probe the hot band absorption of the molecules by re-excitation into S1. The total fluorescence as a function of probe laser wavelength is observed. The excitation spectrum is broad and featureless in the red but shows sharp structure in the vicinity of the pump laser wavelength. However, the sharp structure depends on the portion of the rotational contour excited. The experimental results show that the redistribution of energy is nonstatistical among the isoenergetic levels. This is explained by assuming that combination bands of low quanta of vibrations are the accepting levels in the internal conversion process and that these accepting levels undergo slow energy redistribution.

Amplification and excited state absorption in longitudinally pumped laser dyes

Direct measurements of optical gain using a probe laser beam for the laser dye cresyl violet perchlorate (CVP) in methanol solution using longitudinal pumping at two different wavelengths are described. An analysis of these longitudinal pumping experiments is developed and analytical expressions relating measured gain to the measured pump laser transmission are presented. This analysis is developed in terms of relevant optical cross sections including the influence of excited state absorption. The results demonstrate the influence of excited state absorption at the pump wavelength on pumping efficiency and on the gain per pass at the probe laser wavelength.