MEASUREMENT OF MOLECULAR-HYDROGEN DENSITIES BY RESONANCE FLUORESCENCE

Using a pulsed capilary discharge through helium as a light source fluorescence within the Lyman bands (transition X 1 ∑ g + →B 1 ∑ u + of molecular hydrogen and deuterium has been investigated. Selecting a narrow spectral range (width ≈ 8 Å) from the continuum radiation with a spectrometer, lines in the wavelength range from 1060 Å to 1110 Å have been excited having a vibrational quantum number υ″=0 in the lower state, and ≦υ′≦4 in the upper state. The fluorescence intensity has been measured as a function of υ′ and of the hydrogen density. Agreement with calculations has been found to be within ±30%. The method at present allows the determination of densities between 1010 and 1015 molecules per cm3 with a temporal resolution of 1μs and with a spacial resolution of 0.1 cm3 © 1979 Springer-Verlag.