Emission of phosphorescence from biacetyl surface by collision of N2(A 3Σ+u)

A supersonic beam of nitrogen molecules was excited to the A 3Σ+u state by electron impact and was allowed to collide with a biacetyl surface cooled at 77 K. The spectrum of the emission from the surface observed in the 500–580 nm region was assigned to the phosphorescence of biacetyl. Its lifetime, 1.0±0.1 ms, measured from the time dependence of the phosphorescence is found to be shorter than that measured by use of laser excitation (308 and 380 nm) from the same surface, 1.30±0.02 ms. These results are interpreted by a mechanism of triplet–triplet energy transfer from N2(A) (gas) to biacetyl (solid). The quantum yield of the phosphorescence is estimated to be about 1×10−3. The applicability of this method for detection of N2(A) or other low‐lying metastable states is discussed.

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