Knowledge Bank

Single-photon Laser Induced Fluorescence has been used to measure the trans-rotational temperature of mildly vibrationally excited carbon monoxide ($v\prime \prime \le 9$) within the positive column of a CO/He normal d.c. glow $discharge.a$ A tunable, narrowband ArF excimer laser at 193nm was used to pump the strongly allowed $COX1\sum +(v\prime \prime =7)\to A1\Pi (v\prime =1)$ transition with subsequent collection of the 200.8nm (1,8) $4th$ Positive $emission.b$ The resulting rotational spectral peaks were assigned and a subset was used to estimate the rotational temperature to be $432\pm 72K(3\sigma )$. Fourier Transform-InfraRed spectroscopic measurements of this plasma were in good agreement at $395\pm 10K$. These results indicate that within a normal glow discharge environment, CO $4th$ Positive LIF is well suited as a temperature diagnostic.