INFRARED-SPECTRUM OF CH3+ INVOLVING HIGH ROVIBRATIONAL LEVELS

An extensive search of carbo-ion spectra in the infrared region from 3 300 cm(-1) to 2900 cm(-1) has revealed many spectral lines of CH3+, th e most fundamental hydrocarbon cation. Out of over 1000 spectral lines that were identified as due to CH3+ from their plasma chemical behavi ors and linewidths, 356 lines have been assigned to the CH stretch v(3 ) fundamental band. Most of the remaining lines are thought to belong to the hot bands v(2) + v(3) - v(2) and v(3) + v(4) - v(4). Their anal ysis was found to be difficult because of the large Coriolis interacti on and the near degeneracy of v(2) and v(4). A series of spectral line s has been assigned to the v(3) + v(4) - v(4) band. The rovibrational temperature of CH3+ in the plasma has been determined from relative in tensities of the spectral lines.