Predicted rovibronic spectra of CH2+ and CD2+

We present simulations of the (A) over tilde B-2(1) <-- (X) over tilde (2)A (1) electronic band systems of CH2+ and CD2+ in absorption at 200 K, For ea ch isotopomer we calculate the spectrum over the range from 5000 to 18 000 cm(-1) for the purpose of assisting the experimental search of the spectrum in a cooled hollow-cathode discharge. We make use of our previously determ ined ab initio potential energy surfaces, dipole moment and transition mome nt surfaces in a calculation that includes the Renner-Teller effect and spi n-orbit coupling. To complete the picture we also present simulations of th e rotation and rotation-vibration spectra of CD2+. (C) 2001 Elsevier Scienc e B.V. All rights reserved.