Luminescence of Inorganic Nitrite Salts

Abstract

Nitrite salts of the post-transition-series metals exhibit a long-lived luminescence centered at ∼5500 Å. This emission is characteristic of both the solid state and frozen glassy solutions. It is suggested that this emission originates in a triplet state (T1) of the system, and that, in fact, it is a phosphorescence of T1→S0 molecular type connecting with the ground singlet state (S0). It is shown that the spin–orbit coupling responsible for the enhanced intersystem crossing is introduced by the metal counterion and that such introduction is also dependent on the presence of nitrite-counterion covalency. The increased spin–orbit coupling is manifested in the following ways: (i) a decrease in the phosphorescence lifetime, τp, (ii) an increase in the relative quantum yield ratio Φp / Φf of phosphorescence to fluorescence, (iii) an increase in the T1←S0 absorptivity—which absorptivity is responsible for the yellow-orange colors of the heavy-metal nitrites.

Excited state properties of silver(I) nitrite complexes: Nitrogen conproportionation in Ag(NH3)NO2 induced by LLCT excitation

“…2) at k max = 550 nm. This emission has been previously observed and suggested to originate from the nitrite np * IL triplet [7][8][9][10]. In the excitation spectrum, the 450 nm band appears as a distinct inflection (Fig.…”

“…In diluted aqueous ammonia (0.1 M) both reactions, (1) and (2) The electronic structure [12] and spectra [6,7,9,10] of simple metal nitrites have been discussed in some detail. There is a general agreement on the nature of the lowestenergy excited states, including the np * nitrite IL triplet which absorbs around 450 nm and emits near 550 nm.…”

Color phenomenon in post-transition-metal salts

“…This is hardly surprising because it is very difficult to handle these systems: Many of the heavy-metal salts are only sparsely soluble (<10-3 M); decomposition in solution, particularly at high T and low pH, is common;27 decomposition often generates dissolved C102 gas which Pb(II) 7 x 10"s 5 X 1(TS a z is the principal axis (Clv) and x is perpendicular to the NO," plane. The x, y, z notations denote polarization directions (from refs [16][17][18][19].…”

Spin Polarization in the Triplet State of Silver Nitrite

“…integrand of this operator can sometimes be disentangled by various methods Ce.g., the equation of motion method,3 the Lie algebra method 4 ) and the integration subsequently performed, we point out in this Note that the actual integration can be completely circumvented in some cases by use of a commutator technique.…”