Spectra of C-3 in Solidified Gases at 4 degrees and 20 degrees K

Wavelength, linewidth, and intensity measurements have been made from 3000 to 4500 angstrom of the spectra of triatomic carbon molecules trapped in solid matrices of Ar, Kr, Xe, O-2, N-2, CO2, and SF6 at 4 degrees and 20 degrees K. The carbon source was a Knudsen cell, operated at temperatures up to 2900 degrees K, from which effused a molecular beam with known densities of C-3. Absorption transitions are assigned to vibrational levels of both upper and lower states of the (1)Pi(u)-X (1)Sigma(+)(g) 4050-angstrom group of C-3. The fundamental vibrational frequencies v(1) and v(2) for the upper (1)Pi(u) state, v(2) for the ground (1)Sigma(+)(g) state, and Renner constants for v(2) of the (1)Pi(u) state in these matrices are given. Measurements of absorption intensities give an oscillator strength, averaged for all matrices, equal to 6x10(-2) for the C-3 group. Little or no matrix effect on the intensities is found. However, experimentally determined corrections to the intensities are necessary for effects caused by apparent diffusion of carbon in the matrices to form nonabsorbing carbon aggregates. C-3 linewidths vary with matrix from 40 to 500 cm(-1), and C-3 line shifts vary from -410 to 1065 cm(-1). All matrix shifts are to the red except in the case of the CO2 matrix. No definite effect of temperature on linewidths or shifts is found.