Luminescent mechanochromism has been intensively studied in the past few years. However, difference anisotropic grinding and isotropic compression is not clearly distinguished many cases, spite of importance this discrimination for application such mechanochromic materials. We now report distinct luminescent responses a new organic fluorophore, tetrathiazolylthiophene, to these stresses. The multichromism achieved over entire visible region using single fluorophore. different mechanisms blue...

Infrared measurements at room temperature have shown that the hydrogen-bond symmetrization occurs 62.1 GPa in ice. The OH stretching frequency initially located 3500 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ ambient pressure falls toward zero around 60 GPa. An absorption band appears low-frequency region below 800 about 65 GPa, growing a definite peak with shift to high by further compression. Such turn dependence of is an evidence for transition from ice VII symmetric X. bending disappears...

Despite many experimental and theoretical studies, the crystal structure of $\ensuremath{\epsilon}$ phase solid oxygen has not been determined. We performed powder x-ray diffraction experiments Rietveld analyses in this study to show that a new arrangement monoclinic space group $C2/m$ could fit patterns obtained consisted an ${\mathrm{O}}_{8}$ cluster with 4 molecules. The dependence lattice parameters, molar volume, intermolecular distances on pressure was investigated.

Nondestructive observation of anomalously preserved methane (CH4) hydrate stored outside its thermodynamically stable zone below the melting point ice was performed at 193 K. By use two different types phase contrast X-ray imaging techniques, interferometric and diffraction enhanced imaging, it shown that CH4 under anomalous preservation conditions completely enveloped stabilized by a thin layer ice. The thickness inhomogeneous, with an average about 100 μm after storage for 24 h 253 These...

X-ray diffraction study of solid CO(2) at room temperature has shown that the powder pattern high-pressure phase, which supersedes low-pressure cubic Pa3 phase about 10 gigapascals, is consistently interpreted in terms an orthorhombic Cmca structure. The cell 11.8 gigapascals dimensions 4.330 +/- 0.015, 4.657 0.005, 5.963 0.009 angstroms for its a, b, and c faces, respectively, a volume 120.3 0.5 angstroms. Four molecules contained unit are located base-centered positions with their...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInfrared study of vibrational property and polymerization fullerene C60 C70 under pressureH. Yamawaki, M. Yoshida, Y. Kakudate, S. Usuba, H. Yokoi, Fujiwara, K. Aoki, R. Ruoff, Malhotra, D. LorentsCite this: J. Phys. Chem. 1993, 97, 43, 11161–11163Publication Date (Print):October 1, 1993Publication History Published online1 May 2002Published inissue 1 October...

Sodium borohydride dihydrate (NaBH4·2H2O) forms through dihydrogen bonding between the hydridic hydrogen of BH4- ion and protonic water molecule. High-pressure structural changes in NaBH4·2H2O, observed up to 11 GPa X-ray diffraction Raman scattering spectroscopy, were analyzed assess influence bonds on its crystal structure. At approximately 4.6 GPa, certain broken, leading decomposition NaBH4·2H2O into ambient pressure phase NaBH4 (α-NaBH4) ice VII. Upon further compression beyond 6.6...

The infrared absorption spectra of ${\mathrm{H}}_{2}\mathrm{O}$ and ${\mathrm{D}}_{2}\mathrm{O}$ ices were measured with a diamond-anvil cell up to 141 GPa at 298 K. high-pressure corrected for diamond provided the substantial profile over whole pressure range measured. A sequence pressure-induced Fermi resonance was observed between softening stretch mode combinations rotational bending modes below 55 as reported previously. One showed an abrupt increase in peak frequency...

High-pressure infrared spectra were measured in a diamond anvil cell at room temperature and pressures up to 13.7 GPa. Transitions from liquid crystalline cubic orthorhombic phase observed the molecular 0.7 1.0 GPa, respectively. Polymerization occurred 4.2 accompanied by appearance of new peaks indicating formation CC double saturated C−C single bonds. The bonds showed an increase quantity on further compression beyond 4 while no significant change. spectrum reaction product recovered 14...

We have experimentally observed that the optical absorption spectra of single-walled carbon nanotube (SWCNT) films change drastically and reversibly by pressure up to 4.1 GPa. The main feature at 0.68 eV attributed interband transition in semiconducting nanotubes [chiral $(n,m)$ zigzag $(n,0),$ with $n\ensuremath{-}m\ensuremath{\ne}3i]$ shifts lower energy eventually vanishes increasing pressure. Accordingly, we infer electronic structure properties SWCNTs solid state are highly sensitive...

Infrared spectra at high pressure and room temperature reveal that molecular dissociation metallization occur in solid ${\mathrm{H}}_{2}\mathrm{S}$ near 46 96 GPa, respectively. The disappearance of SH stretching bands the $2300--2500{\mathrm{cm}}^{\ensuremath{-}1}$ region simultaneous appearance a lattice vibrational mode around $1300{\mathrm{cm}}^{\ensuremath{-}1}$ signal dissociation. At higher pressures, low-energy electronic absorption band develops eventually extends throughout...

Fermi resonance was observed between the OH stretch and overtone of bending modes HDO molecules contaminated in phase VII D(2)O ice over pressure range from 17 to 30 gigapascals. An anharmonic coupling constant, which is related potential energy surface on hydrogen-bonded protons oscillate, found around 50 wave numbers through resonant range. Its experimentally obtained magnitude pressure-insensitive behavior will be useful for theoretical studies hence nature hydrogen bonding ice.

The long-unknown crystal structure of the high pressure phase scandium-II was solved by powder x-ray diffraction and found to have tetragonal host channels along $c$ axis guest chains that are incommensurate with host, as well phases $\mathrm{Ba}$, $\mathrm{Sr}$, $\mathrm{Bi}$, $\mathrm{Sb}$. dependences lattice constants, incommensurability, atomic distances, volume were investigated.

The crystal structure of the binary clathrate hydrate methane (CH4) and ethanol was identified by powder X-ray diffraction. Raman spectroscopic measurements were also performed. Because hydrogen bonding between water molecules likely affects formation its stability, role for stability is important a further understanding guest−host interactions in complex inclusion compounds. In this study, we provide evidence occupation with CH4 II hydrate, whereas one inhibitors formation. cage occupancies...

There are six known phases for phosphorus at room temperature under high pressure. Only the structure of phase IV, which exists from 107 GPa to 137 GPa, remains unsolved. We performed a powder x-ray diffraction experiment and Rietveld analysis successfully determined its be an incommensurately modulated by only 1 site atomic position. High-pressure halogens chalcogens have previously been shown similar structure; however, IV is different them was third case.

The recently discovered high pressure phase VII of calcium [M. Sakata et al., Phys. Rev. B 83, 220512(R) (2011)] has the highest superconducting transition temperature (T(c)) 29 K among all elements. Understanding cause for such a T(c) state is necessary to clarify its crystal structure. structure this was determined by an x-ray powder diffraction experiment and density functional theory calculation not found be usual host-guest type but consisted 2×2 supercell in tetragonal ab plane with...

The phase diagram of the dense ices VII, VIII (molecular phases), and X (nonmolecular phase) was investigated over a $P\ensuremath{-}T$ region 12-298 K 2-100 GPa by infrared absorption measurements. ice VII-VIII VIII-X boundaries determined in this study agree with those provided previous Raman studies. VII-X transitions can be characterized completion rotational to distortional mode conversion (the disappearance ${\ensuremath{\nu}}_{R}$ peak), boundary accordingly. Triple points among three...

Infrared absorption spectra of ice VII have been measured up to 100 GPa at room temperature. The OH stretching peaks, which showed a rapid shift low frequency with an enormous line broadening increasing pressure, were found interfere the bending and librational peaks very high pressures above 40 GPa. Appearance such Fano-type interference in shape indicates that modes form continuous (or quasicontinuous) energy band their excitation state. formation continuum is closely related conversion...

Near ambient pressures, molecular diffusion dominates protonic in ice. Theoretical studies have predicted that will dominate at high pressures We measured the coefficient for highest temperature phase of ice VII 400 kelvin over its entire stable pressure region. The values ranged from 10(-17) to 10(-15) square meters per second 10 63 gigapascals. coefficients extrapolated temperatures close melting curve were less by a factor 10(2) 10(3) than superionic criterion approximately 10(-8) second,...

The structure of high pressure phases, $\text{selenium}\text{\ensuremath{-}}{II}^{\ensuremath{'}}$ $(\mathrm{Se}\text{\ensuremath{-}}{II}^{\ensuremath{'}})$ and sulfur-II (S-II), for $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Se}}_{8}$ (monoclinic Se-I) $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{S}}_{8}$ (orthorhombic S-I) was studied by powder x-ray diffraction experiments. $\mathrm{Se}\text{\ensuremath{-}}{II}^{\ensuremath{'}}$ S-II were found to be isostructural belong the...

We performed powder x-ray experiments on hydrogen sulfide $({\mathrm{H}}_{2}\mathrm{S})$ under high pressure at room and low temperatures. Phase V appearing above $27\phantom{\rule{0.3em}{0ex}}\text{GPa}$ temperature was confirmed by x ray to be associated with a molecular dissociation. The dissociation first observed $150\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ higher around $43\phantom{\rule{0.3em}{0ex}}\text{GPa}$. Two new low-temperature high-pressure phases ${\text{III}}^{\ensuremath{'}}$...

An x-ray-powder-diffraction experiment on solid ${\mathrm{H}}_{2}\mathrm{S}$ was performed with a diamond-anvil cell and an image plate to determine the unknown structures of phases ${\mathrm{I}}^{\ensuremath{'}}$ IV up 25 GPa at room temperature. The were found be cubic ${T}^{4}{\ensuremath{-}P2}_{1}3$ tetragonal ${D}_{4h}^{20}{\ensuremath{-}I4}_{1}/acd,$ respectively, by Rietveld method. Both derived from fcc structure phase I slight atomic displacements sulfur. Likely positions hydrogen...

Ammonia borane (NH3BH3) is a promising hydrogen-storage material because of its high hydrogen density. It employed as source when synthesizing superconducting polyhydrides under pressure. Additionally, NH3BH3 crystallographically interesting compound that features protonic (Hδ+) and hydridic (Hδ−), it forms dihydrogen bond, which explains stable existence solid. Herein, X-ray diffraction experiments were performed at pressures (HPs) temperatures (HTs) up to 30 GPa 300 °C, respectively,...

The crystal structure of the high-pressure phase hexahydro-1,3,5-trinitro-1,3,5-triazine (gamma-RDX), which is stable above 4 GPa at room temperature, was investigated by using infrared spectroscopy and powder X-ray diffraction measurements followed Rietveld refinements a diamond anvil cell (DAC). Although gamma alpha phases were found to belong same space group Pbca, they exhibited different packing. molecular conformation as that phase; however, torsion angles N-NO2 changed marginally.