Knowledge Bank

Discharge by Diode laser Spectroscopy We have measured the drift velocity and the mobility of $ArH+$ ions in a helium DC glow discharge by observing the drift velocity induced Doppler effect frequency shifts of the ions infrared absorption lines at $4\mu m.1$ The shifts are comparable to the line width, $\sim$100 MHz, and correspond to a drift velocity of $\sim 4\times 104$ cm $s-1$. From pressure, temperature, and axial electric field measurements we obtain a reduced nobility of $ArH+$ in He of $19\pm 4(2\sigma )$ $cm2/(V-s)$ which is in excellent agreement with the earlier mass spectroscopic drift tube result of $19.2\pm$ $1.6cm2/(V-s).2$ Preliminary tests of the $ArH+$ v and J dependence of the Doppler shift have been mode. 1. J. W. Brault and S. P. Davis, Phys. Scrip. 25 268 (1982). 2. W. Lindinger and D. L. Albritton. J. Chem. Phys. 62 3517 (1975)