Optical evidence for Rh(II) in a NaCl lattice

Optical transitions ofRh2+in NaCl crystals studied by electron spin resonance and magnetic circular dichroism

“…Our ESR correlated MCD and optical absorption data do not agree with the optical absorption result for Rh 2ϩ presented in Ref. 9. We do not detect an optical absorption around 19 350 cm Ϫ1 and, more importantly, the MCD spectrum shows no paramagnetic band of reasonable intensity at this energy.…”

“…In Ref. 9, the crystals were annealed to 500-600°C which produced a high density of macroscopic optical scattering inclusions and resulted in samples of poor optical quality. Our ESR analysis has shown that after such a thermal anneal the dominant species is the O͑II͒ Rh 2ϩ center.…”

DFT study of the Jahn–Teller impurity Rh2+ in octahedral symmetry

“…Görller‐Walrand et al 21 studied the optical absorption spectrum due to a NaCl crystal doped with Rh 3+ and annealed at 600°C. Below 2.75 eV such authors report only one band peaked at 2.4 eV which is attributed to Rh 2+ .…”

Behaviour of Rh supported on hydroxyapatite catalysts in partial oxidation and steam reforming of methane: On the role of the speciation of the Rh particles

“…For the sake of comparison, the spectrum of the Rh(2)/HAP sample reduced at 773 K was also included. The attribution of the absorption bands was carried out by comparison with spectra of earlier studies dealing with rhodium complexes [35][36][37][38][39][40][41][42][43].…”

“…It is known that the trivalency is definitely the most stable oxidation number among Rh ions in oxides [35]. The typical spectrum of Rh 3+ (4d 6 ) is composed of two bands in the visible domain describing two allowed d-d transitions ( 1 A 1g → 1 T 1g (at 535 nm) and 1 A 1g → 1 T 2g (at 420 nm)) [35,36,43]. The Rh 2+ (3d 7 ) ions also exhibit a simple spectrum that involves two d-d transitions ( 2 E g → 2 T 1g and 2 E g → 2 T 2g ) appearing in the visible domain.…”