Structure of solid carbon diselenide (CSe2) at 17.5, 50 and 200K

Confinement of selenium inside carbon nanotubes. Structural characterization by X-ray diffraction and X-ray absorption spectroscopy

“…The type of cation of the zeolite was found to play a role on the Se chain/Se ring ratio as reported in Poborchii et al [7]. Theoretical work on Se clusters and infinite chains in cages of zeolite Linde type A based on energy consideration [11] allowed the authors to determine that the most stable clusters are Se 8 , Se 12 and Se 16 in such an environment. In the form of chains or rings, Se is twofold-coordinated in the nearest shell.…”

“…Another feature appears, called C, located at +4.5 eV from M whose intensity increases when the tube diameter decreases. The energy edge shift by 1 eV from bulk Se to Se12 is a strong indication of Se-C bonds occurrence: Se K edge shift has been observed in the case of selenate and selenite [15][16][17][18][19][20][21][22][23][24][25][26][27][28]. It is typical of bonds with light atoms and thus oxidation state.…”

“…The structural organization of selenium has been characterized with special care to C atom detection around Se, since Se has already been shown to display bonds with C [15] and a carbon diselenide is mentioned [16,17]. The goal of the paper is to present the effect of confinement due to the nanotube diameter decrease on the transition from chain to ring and on the possible occurrence of C-Se bonds.…”

The crystal structure of formaldehyde

“…The d-paraformaldehyde was supplied by MSD Isotopes, Canada Ltd. A powder sample in the crystalline phase was prepared by a modification of the cryogrinding technique developed by Powell et al [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. In the present case the 'as supplied' powder was heated, to convert it to vapour, and then recondensed as a solid in the thin-walled vanadium sample chamber held at 77 K. The crystalline phase can only be formed by vapour deposition directly on to a cold substrate and so the vapour transport system was constructed to prevent the formation of both the liquid phase and the high temperature polymer phase.…”

“…In an extensive program of investigation into the structures and dynamics of molecular solids composed of simple molecules, we have previously determined the crystal structures of several molecular crystals using the technique of neutron powder profile refinement I- [1][2][3][4][5][6]. The molecular dynamics of several of these solids has been studied using both optical [7,8] and inelastic neutron scattering techniques [9].…”