14N/15N isotope effect in the UV photodissociation of N2O

14N216O, 14N15N16O and 15N14N16O were photolyzed between 202 and 206 nm. The photodissociation products, O(1D2) and N2(X 1∑g+), were monitored by a resonance-enhanced multiphoton ionization technique. The O(1D2) signal was weaker when the heavy isotopomers were photolyzed at 205.47 nm. The isotope effect was as large as 10% for 14N15N16O, while it was 3% for 15N14N16O. The absorption coefficients must be smaller for the heavy isotopomers. An inverse isotope effect was observed when N2(X 1∑g+) was monitored via the a″ 1∑g+ state. 14N2 signal was less than that for 14N15N. There must be an isotope effect in the detection efficiency of highly rotationally excited N2(X 1∑g+).