Pulsed, time-resolved photoacoustic

J. E. Rudzki, J. L. Goodman, K. S. Peters. Simultaneous Determination of Photoreaction Dynamics and Energetics Using Pulsed, Time-Resolved Photoacoustic Calorimetry. J.Am. Chem. Soc. 1985, 107, 7849-7854. 

Due to its thermal instability, the ring structure of trans-cycloheptene (39a) has only been characterized in trans-2-cycloheptenone (41) by its IR spectrum and by trapping experiments (47). To date, no direct structural evidence has been found for trans-cyclohexene (43a). It seems likely, however, that trans-l-phenylcyclohexene (43b) is the species detected by pulsed time-resolved photoacoustic calorimetry (cf. Section III. B) (48). 

Pulsed, time-resolved photoacoustic calorimetry employs a pulsed uv laser source to induce a photochemical reaction in the molecule of... 

Goodman, J.L., Peters, K.S., Misawa, H., and Caldwell, R.A., Use of pulsed time-resolved photoacoustic calorimetry to determine the strain energy of tra s-l-phenylcyclohexene and the energy of the relaxed 1-phenylcyclohexene triplet, /. Am. Chem. Soc., 108, 6803-6805,1986. 

Time-resolved Photoacoustic Spectroscopy. In photoacoustic spectroscopy (PAS) the heat evolved by the absorption of light in the sample is transformed into sound waves which are detected by a microphone. In steady-state spectroscopy the light is continuous, but it is also possible to use a pulsed laser and to observe the change in the intensity of the sound signal with time. In this respect time-resolved PAS is somewhat similar to thermal lensing, but both techniques have different limitations and advantages. 

Many spectroscopic methods have been employed for the investigation of such systems For example, wide-band, time-resolved, pulsed photoacoustic spectroscopy was employed to study the electron transfer reaction between a triplet magnesium porphyrin and various quinones in polar and nonpolar solvents. Likewise, ultrafast time-resolved anisotropy experiments with [5-(l,4-benzoquinonyl)-10,15,20-triphenylpor-phyrinato]magnesium 16 showed that the photoinduced electron transfer process involving the locally-excited MgP Q state is solvent-independent, while the thermal charge recombination reaction is solvent-dependent . Recently, several examples of quinone-phtha-locyanine systems have also been reported . 

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