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In K 2 [RuCl 5 NO] light-induced long-living metastable states can be generated similar to those in Na 2 [Fe(CN) 5 NO] · 2H 2 O and other nitrosylprussides revealing the decisive role of the NO ligand for the formation of the new states. With Raman spectroscopy intramolecular and lattice vibrations were investigated during the population process and in the state of saturation. Only the frequencies of the internal modes are shifted. The thermally induced decay was investigated by differential scanning calorimetry, yielding information about the decay temperature, the activation energy, the frequency factor and the order of reaction.

When excited by the 514.5 nm radiation of an argon ion laser at temperatures below 150 K crystalline sodium nitroprusside Na2[Fe(CN)5NO] · 2H2O can be transformed into an extremely long-living metastable state. The Raman spectra of the crystal in the metastable state and ground state are compared in the range of 50–2350 cm-1. In the metastable state the ṽ(NO)-stretching vibration is shifted by more than 100 cm-1 to smaller frequencies depending on the orientation of the sample with respect to the crystallographic axis. This indicates the population of the antibonding π∗(NO)-orbital. In addition two new vibrations appear at 566 and 422 cm-1. The other vibrational frequencies of the molecular ion [Fe(CN)5NO]2- are scarcely shifted, but relative intensities change.

We have investigated the Raman enhancement of benzene, chemisorbed on small platinum clusters. The size of the clusters was small compared to the wavelength of the excitation source. We observe a strong wavelength dependence of the enhancement with stronger enhancement at shorter wavelengths and amount of 10 3 -10 4 compared with those wavelengths where no enhancement could be observed. All vibrations normally Raman-active in the free molecule are enhanced. In addition, some other bands are found, which are one order of magnitude weaker and which may be assigned to normal Raman inactive vibrations.

The absorption spectra of Na2[Fe(CN)5NO] · 2H2O were measured in the visible region in the range of 3400–7000 A. In the metastable state, an additional absorption band in the long wavelength range is observed and the transition 2 b 2 (d xy )→ 7 e(π ∗ −NO ) becomes weaker in the excited state indicating a population of the π∗(NO)-orbital. The laser excited emission spectrum shows a broad luminescence beginning at the excitation line λ = 5145 A ( 19,436 cm -1 ) with a maximum at about 6250 A (16,000 cm-1). A strong sharp luminescence at about 7836 A is registered and may be assigned to a transition 3b1(dx2−y2) or 5a1(dz2) to the antibonding π∗(NO)- orbital. Further the broad luminescence is superimposed by a series of sharp spikes. These sharp spikes can also be observed for several days, when the laser is switched off, and are depending on the crystal orientation.

The temperature dependence of the elastic constants of cubic K2Hg(CN)4 has been measured by optical Brillouin spectroscopy in the temperature range from 300-110 K. A decrease of all three elastic constants was found in agreement with the results of ultrasonic measurements. Raman measurements in the temperature range from 300-4 K revealed a splitting of the F2g modes corresponding to a trigonal distortion of the Hg(CN)4-tetrahedra in the low temperature phase.

We demonstrate for the first time that excitation of silver containing rare gas matrices at 406.74 nm results in resonance Raman spectra which show low energy localized and resonant modes. As they combine with the Ag2 stretching vibration and its overtones, they can unambiguously be attributed to the Ag2 molecule. In Xe-matrices the coupling of lattice phonons and impurity vibrations is documented by side bands which resemble the phonon density of states of the host lattice. Two trapping sites are observed in Kr-matrices.

The temperature dependence of the elastic shear constant C44 of cubic potassium cyanide has been measured by optical Brillouin spectroscopy in the temperature range from 300-168 K. A strong softening of the constant C44 was found in agreement with the results of ultrasonic and neutron measurements.