Dense, Subnano Phase of Clustered O-2

Year: 2019

Authors: Santoro M., Dziubek K., Scelta D., Morana M., Gorelli FA., Bini R., Hanfland M., Rouquette J., di Renzo F., Haines J.

Autors Affiliation: CNR, INO, Ist Nazl Ott, I-50019 Sesto Fiorentino, Italy; European Lab Non Linear Spect LENS, I-50019 Sesto Fiorentino, Italy; CNR, ICCOM, Ist Chim Composti Organometallici, I-50019 Sesto Fiorentino, Italy; Univ Firenze, Dipartimento Chim, I-50019 Sesto Fiorentino, Italy; European Synchrotron Radiat Facil, F-38343 Grenoble, France; Univ Montpellier, CNRS, ENSCM, ICGM, F-34095 Montpellier, France; Univ Pavia, Dipartimento Sci Terra & Ambiente, I-27100 Pavia, Italy.

Abstract: Condensed O-2 tends to form clusters, even with a long-range order. In particular, in solid oxygen, strong intermolecular charge transfer at high pressures leads to the formation of (O-2)(4) tetramers above 10 GPa, in the epsilon-O-2 phase, with weak O-2-O-2 chemical bonds. Indeed, epsilon-O-2 is entirely made of these tetramers. We conducted experimental investigations on strongly densified O-2 in a different environment, that is to say in the form of a subnano phase build up within the 1D microchannels of a purely siliceous, inert zeolite, TON, at pressures of 0.520 GPa, by means of diamond anvil cells. Our X-ray diffraction and infrared and Raman spectroscopy results consistently show that oxygen forms clusters in this nanophase, above 10 GPa, similar to epsilon-O-2, except that the clusters are rather of the type of weakly bonded (O-2)(2) dimers in this case. Also, by analogy with bulk oxygen, we show that the O-2 spin within the dimers departs from S = 1 toward lower values, upon increasing pressure. Our findings thereby add to the general view on essential properties of highly dense oxygen.

Journal/Review: JOURNAL OF PHYSICAL CHEMISTRY C

Volume: 123 (14)      Pages from: 9651  to: 9657

More Information: We acknowledge the PRIN project ZAPPING, number 2015HK93L7, granted by the Italian Ministry of Education, Universities and Research, MIUR. We are also grateful for the support from PICS bilateral project CNR/CNRS (Italy/France), 2014-2016: Multifunctional zeolite/polymer nano composites. We also thank the Deep Carbon Observatory (DCO) initiative under the project Physics and Chemistry of Carbon at Extreme Conditions and the Ente Cassa di Risparmio di Firenze under the project Firenze Hydrolab 2.
KeyWords: EPSILON-PHASE; PRESSURE; SILICA; OXYGEN
DOI: 10.1021/acs.jpcc.9b02476

Citations: 2
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