title: High pressure Raman spectra of monoglycine nitrate single crystal.
abstract: Single crystal of monoglycine nitrate has been studied by Raman spectroscopy under high pressures up to 5.5 GPa. The results show changes in lattice modes in the pressure ranges of 1.1-1.6 GPa and 4.0-4.6 GPa. The first change occurs with appearance of bands related to the lattice modes as well as discontinuity in the slope of dΩ/dP of these modes. Moreover, bands associated with the skeleton of glycine suggest that the molecule undergoes conformational modifications. The appearance of a strong band at 55 cm(-1) point to a second phase transition associated with the lattice modes, while the internal modes remain unchanged. These anomalies are probably due to rearrangement of hydrogen bonds. Additionally, decompression to ambient pressure shows that the phase transitions are reversible. Finally, the results show that the nitrate anions play an important role on the stability of the monoglycine nitrate crystal.
authors.affiliation: Universidade Federal do Maranhão, CCSST, Imperatriz, MA 65900-000, Brazil; Instituto Federal do Tocantins, Araguaína, TO 77826-170, Brazil.
authors.forename: J O
authors.initials: JO
authors.lastname: Carvalho
authors.affiliation: Universidade Federal do Maranhão, CCSST, Imperatriz, MA 65900-000, Brazil; Universidade Federal do Sul e Sudeste do Pará, ICEN, Marabá, PA 68505-080, Brazil.
authors.forename: G M
authors.initials: GM
authors.lastname: Moura
authors.affiliation: Universidade Federal do Maranhão, CCSST, Imperatriz, MA 65900-000, Brazil.
authors.forename: A O
authors.initials: AO
authors.lastname: Dos Santos
authors.affiliation: Universidade Federal do Maranhão, CCSST, Imperatriz, MA 65900-000, Brazil.
authors.forename: R J C
authors.initials: RJ
authors.lastname: Lima
authors.affiliation: Universidade Federal do Ceará, Campus do Pici, Fortaleza, CE 60455-760, Brazil.
authors.forename: P T C
authors.initials: PT
authors.lastname: Freire
authors.affiliation: Universidade Federal do Maranhão, CCSST, Imperatriz, MA 65900-000, Brazil. Electronic address: freitasfacanha@gmail.com.
authors.forename: P F
authors.initials: PF
authors.lastname: Façanha Filho
keywords: High pressure; Monoglycine nitrate; Raman spectroscopy