Knowledge Bank

We have used the technique of spatially-resolved matrix isolation spectroscopy to illucidate the photochemical action spectrum of the $Cr(CO)6-Cr(CO)5-Cr(CO)4$ photochemical system in an Ar matrix. In this technique, we exploit the fact that each position on a matrix isolation sample is potentially the site of a different experiment. Here, we labeled each position parametrically with a unique photolysis wavelength produced by passing a continuum source through a simple quartz prism. The dispersed lamp spectrum was splayed across the matrix, and a spartially uniform probe beam at one wavelength imaged through the matrix onto a linear photodiode array detector allowed us to observe the changes in species' concentrations at all photolysis wavelengths in a single experiment. In the $Cr(CO)6$ system, we were able to illucidate the photodissociation and photoreversion spectra of the three principle species in spite of the fact that the absorption spectra were highly overlapped. The low energy absorption band of $Cr(CO)4$ was identified in this way for the first time.