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Isotope Shifts of Zero-Phonon Transition in Highly Purified NaNO2 Crystal

Low temperature optical spectra of highly purified NaNO 2 crystals have been investigated in near u v region. The width of the zero-phonon absorption line at ν 00 due to the electronic transition 1 A 1 → 1 B 1 in NO 2 - is remarkably reduced in the purified crystal and three satellite absorption lines are observed separately from the high energy tail of the strong zero-phonon absorption line. The energy separations of these lines from ν 00 are 4 ±1, 6 ±1 and 7.5 ±1 cm -1 and are identified as the isotope shifts of the zero-phonon transition in NO 17 O - , NO 18 O - and 15 NO 2 - , respectively.