Determination of the Einstein A coefficient for the ?→? transition of ammonia-d3

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Abstract
The fluorescence of ND3 has been observed for excitation into the ?←? system at 213.86 nm. The quantum yield for this transition is 8.3×10−5. With this quantum yield and the known rotational linewidth of the upper electronic state, an Einstein A coefficient is obtained that compares favorably with a value calculated from the emission intensity and absorption strength of the (ν1′,ν2′=0,0) ↔ (ν1″,ν2″ =0,2) vibronic bands. The average of these two values is A=3.6±0.3×107 sec−1. The underlying continuum of the ?←? absorption system, attributed to the predissociation of ND3, is invoked to explain most of the discrepancy between the above value for A and that predicted by the equation of Strickler and Berg. A weaker, more diffuse emission has also been observed from ND3 for excitation into the ?←? system at 206.24 nm with fluorescence quantum yield of 1.1×10−5.