EMISSION-SPECTRA OF HIGH RYDBERG STATES IN A PLASMA - STARK-BROADENED NEUTRAL OXYGEN IN THE 7.5-MU-M REGION

Plasma-broadened visible spectra have long been used to infer plasma parameters. In this work we examine the use of high Rydberg states in plasma spectroscopy for low-density plasmas. For low densities the high Rydberg states may be very useful because of their large widths and the fact that they are less susceptible to ion dynamical effects. We have calculated plasma-broadened spectra of the neutral oxygen n = 6 --> n = 5 transition in the 7.5-mu-m region for a temperature around 10 000 K and electron densities 5 X 10(13)-10(16) e/cm3 and found that these spectra can be a useful probe for low-density plasmas. We also describe how selection rules can be used to greatly reduce the computational requirements.