On optical dispersion in transparent molecular systems

Abstract

The M6ssbauer data of the new molecular state of Na2Fe(CN)sNO. 2H20 , generated by coherent light, were investigated, particularly as a function of temperature. Its energetic position is close to the molecular groundstate and separated from the excited electronic states by a wide gap. It is optically generated by an inelastic scattering process. The electric field gradient is solely determined by the asymmetric charge distribution of the valence electrons which have the same symmetry properties as the groundstate. The dynamics of the molecular vibrational oscillators is for the new molecular state identical with that of the groundstate. The thermal conversion of the new states, having infinite radiative lifetime, back to the groundstate is determined at elevated temperatures by a peculiar decay function which solely depends upon the internal thermal agitation of the nitroprusside molecular complex [Fe(CN)sNO] 2-. There is strong evidence that the new molecular state is not a high-spin state. There is no other state of the molecule known which, in terms of its physical properties, its way of generation and decay, is related to the new state reported.

Mössbauer and ESR Study of Long-Lived Photoexcited Species in Sodium Pentacyanonitrosylferrate( ll) Produced by 300-400 NM UV Irradiation at Low Temperatures

“…Mössbauer parameters obtained from deconvolution of the spectra assuming a model with a quadrupole doublet are listed in Table 1 (i). The parameters (I. S. and Q. S.) for the SPN/NaCl disk agreed with the known Mössbauer parameters for SPN [3][4][5]12,13], whereas the line-width for the irradiated disk was remarkably larger than those for the disk before irradiation and after annealing. Hence, the spectrum can also be deconvoluted to one quadrupole doublet ascribed to SPN and two others; another model with three pairs of quadrupole doublets.…”

“…= -0.183 mm/s relative to Fe(Pd) source; Q.S. = 2.736 mm/s) reported for the metastable state produced by irradiation at 400-530 nm [3][4][5]. Hence, it is obvious that the photoexcited product produced by UV irradiation at 300-400 nm in this work is different from the metastable state produced previously by irradiation with visible light.…”

The nature of Ru–NO bonds in ruthenium tetraazamacrocycle nitrosyl complexes—a computational study

“…69,70 These kinds of light-induced metastable states were reported for the first time in 1977, in a Mössbauer-spectroscopical study of sodium nitroprusside dihydrate, SNP. 71,72 Subsequently, the presence of the metastable states of SNP was confirmed by differential scanning calorimetry (DSC). 73 These metastable states are populated when samples are irradiated at low temperature with light of the appropriate wavelength, and they are deactivated to the stable ground state (GS) isomer by red de-excitation or by thermal decay.…”

Ruthenium(II)-nitrosyl polypyridinyl Complexes: from NO/ON Isomerization to NO delivery

“…This intriguing result has led to several patents, and its full understanding is still a challenging issue for theorists [15]. Nevertheless, it is important to point out that this result significantly increases the yield of photoswitch in metal-nitrosyl complexes from 50 % [8] to 92 %. By itself it justifies additional investigations on this material with potential applications in opto-electronic and holography.…”

“…Metal-nitrosyl complexes can also provide alternative candidates. Indeed, sodium nitroprusside has been reported more than 30 years ago for its long-lived photo-induced metastable state, according to the following equilibrium [8]: [Ru II (py) 4 Cl(NO)](PF 6 ) 2 ·1/2H 2 O, in which the ruthenium complex possesses the C 4 symmetry (trans(Cl-NO) isomer) is the first and up to now the only quasi-complete molecular and reversible switch observed at the solid state in the family of metal nitrosyl complexes. This outstanding complex was studied by DSC, IR and X-ray diffraction measurements on powder and single crystal.…”