engleski

New technique for the measurement of reaction constants of photochemically produced NaH

The diffusion of NaH molecules in H2 gas and its reactive loss mechanism are described. The temporal behaviour of photochemically produced NaH in the reactive Na(3p)-H2(v"=2, 3) collision system was observed by means of resonance-enhanced coherent anti-Stokes Raman scattering (RECARS). A simple diffusion model applies well in the lower-pressure region (10 mbar). The binary diffusion constant for NaH molecules in H2, D0=0.7 cm2 /sec at 1 atm and 273 K, was determined. At higher pressures (up to 900 mbar), where the influence of diffusion decreases, an unexpectedly rapid decay of the NaH signal is observed. From this time behaviour we identify a new NaH loss mechanism described by a second-order rate equation in NaH.

binary diffusion constant ; photochemicaly produced NaH ; second-order rate

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