The time-resolved emission spectra from high-voltage pulsed discharges
in liquid helium below 4.2 K, 1 atm, and cryogenic helium gas near 4.
2 K, 1 atm, have been measured in the visible spectral range. In addit
ion to the well known atomic lines, which exhibit strong and broadened
profiles with continua at an early stage, some strong spectral featur
es are observed near 23300 cm(-1) (similar to 430 nm) and 25500 cm(-1)
(similar to 395 nm). The former can be assigned to He-2 transition (g
(3) Sigma(g)(+) - a(3) Sigma(u)(+)), and the latter is not observed in
previously reported works. These features disappear in 77 K and 300 K
, 1 atm. He gas under the same experimental conditions.