INFRARED-LASER SPECTRUM OF THE SI-2(-) ANION IN A SILANE PLASMA

The first rotationally resolved spectrum of the Si-2(-) anion has been detected. The spectrum was recorded in a low pressure air cooled disc harge in mixtures of silane and hydrogen producing amorphous silicon, using infrared laser velocity modulation absorption spectroscopy. Seve nty lines between 740 and 820 cm(-1) were assigned to the A(2) Pi(u1/2 )(v = 1)<--X(2) Sigma(g)(+)(v = 0) subband of Si-2(-). A fit by standa rd Hamiltonians gives precise rotational and fine structure constants for the anion.