We have recorded (11) resonance-enhanced multiphoton ionization spectra of complexes formed between NO and the alkanes: CH_4, C_2H _6, C_3H_8, and n-C_4H_(10). The spectra correspond to the ? ← X? transition, which is a NO-localized 3s ← 2pπ transition. In line with previous work, the spectrum for NO-CH_4 has well-defined structure, but this is only partially resolved for the other complexes. The spectra recorded in the NO-alkane mass channels all show a slowly rising onset, followed by a sharp offset, which is associated with dissociation of NO-alkane, from which binding energies in the X? and ? states are deduced. Beyond this sharp offset, there is a further rise in signal, which is attributed to fragmentation of higher complexes, NO-(alkane)_n. Analysis of these features allows binding energies for (NO-alkane) ? alkane to be estimated, and these suggest that in the NO-(alkane)_2 complexes, the second alkane molecule is bound to the first, rather than to NO. Calculated structures for the 1:1 complexes are reported, as well as binding energies.
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