Etude Spectrometrique De La Lazurite Du Pamir, Tajikistan

Abstract

SOMMAIRELe spectre de résonance Raman de la lazurite du Pamir, au Tajikistan, a été obtenu pour les excitations de 457.9, 488, 514.5, 676 et 1064 nm. Les bandes Raman ont été attribuées aux groupements S 2 -, S 3 et SO 4 -. Une seule progression du centre S 2 a été obtenue avec l'excitation à 457.9 nm, tandis que deux progressions de centres S 3 ont été observées avec l'excitation 514 nm. Les bandes des groupements SO 4 ont une intensité maximale avec les excitations 676 et 1064 nm. Les spectres ultraviolet-visible (UV-VIS), infrarouge (IR) et de résonance paramagnétique électronique (RPE) confirment la présence de ces centres moléculaires. Mots-clés: lazurite, spectrométrie Raman, ions-radicaux moléculaires de soufre, Pamir, Tajikistan. ABSTRACTThe resonance Raman spectrum of lazurite from the Pamir region of Tajikistan has been obtained by the use of 457.9, 488, 514.5, 676 and 1064 nm excitations. The Raman bands are attributed to S 2 -, S 3 and SO 4 sulfur radicals. The vibrational progression of the S 2 radicals is observed only with the 457.9 nm excitation, whereas two progressions of the S 3 centers take place with the 514 nm excitation. The bands of the SO 4 radicals have maximum intensity with 676 and 1064 nm excitations. Ultraviolet-visible (UV-VIS), infrared (IR) and electron spin resonance (ESR) spectra confirm the presence of these molecular centers.

Mineralogical characterization of the blue pigment of Michelangelo's fresco "The Last Judgment"

“…In fact ν 1 , ν 2 , and multiphonon processes as overtones (nν 1 ), and combination bands (nν 1 +ν 2 ) of S 3 -and ν 1 and 2ν 1 of S 2 -have been observed. In contrast to the Raman spectra of lazurite from Pamir and Siberia reported by Ostroumov et al (2002), we were not able to observe effects arising from the presence of SO 4 -groups.…”

“…Unlike in hauyne (Taylor 1967;Burragato et al 1982), the possible contribution to the a-cell parameter variability of K and Cl is not perfectly disclosed in lazurite. Moreover, according to structural and spectroscopic evidence (Evsyunin et al 1998;Ostroumov et al 2002;Di Muro et al 2004), it is clear that at least two more forms of reduced sulfur are also present in lazurite as S 3 -and S 2 -.…”

“…Raman spectroscopy has been widely used to investigate the origin of the various colors in natural and synthetic lazurites (Holzer et al 1969;Daly and Brown 1973;Angell 1973;Clark and Franks 1975;Janz et al 1976;Clark and Cobbold 1978;Ostroumov et al 2002). In particular, the blue to green coloration has been attributed to S 3 -and S 2 -polysulfur radical anions (Cotton et al 1976).…”

Investigation of the painting materials and techniques of the late‐15th century manuscript illuminator Jean Bourdichon

“…As shown in Fig. 5 (top trace) the pigment ultramarine (from the mineral lazurite) is identified by Raman peaks [39,40] at 257 (w), 547(vs), 584 (w), 807 (w,br), 1090 (s), 1121 (m, sh) 1353 (w, br) and 1637 (m) cm −1 . The pigment azurite (Fig.…”

Luminescence and tenebrescence of natural sodalites: a chemical and structural study

“…The Raman band at 987 cm −1 is frequently used as indicator for SO 2− 4 (e.g. Angell 1973;Ostroumov et al 2002;Di Muro et al 2004;Krumrei et al 2007;Frezzotti et al 2012). However, this band occurs in all sodalite spectra collected in this study (Fig.…”