Single-crystal Raman Spectroscopy Research Articles

Polymorphism of the hydroxide perovskite Ga(OH)3 and possible proton-driven transformational behaviour

The crystal structure of hydroxide perovskite Ga(OH)3, the mineral sohngeite, has been determined for a natural sample by single-crystal XRD in space group P42/nmc to R 1 = 0.031, wR 2 = 0.071, GoF = 1.208, and for comparison also in space group P42/n to R 1 = 0.031, wR 2 = 0.073, GoF = 1.076. Unit cell parameters are a = 7.4546(2) A, c = 7.3915(2) A, V = 410.75(2) A3. The two structures are very similar and both have tilt system a + a + c −. The approximate positions of all H atoms in each structure have been refined. In the P42/nmc structure all five H sites are half-occupied, whereas in the P42/n structure four sites are half-occupied and one is fully occupied. The presence of five non-equivalent OH groups in sohngeite is confirmed by single-crystal Raman spectroscopy, but does not allow a choice between these two space groups to be made. There is only a single very weak violator of the c-glide of P42/nmc and the two refined structures are essentially the same, but are significantly different from that of the original description in which orthorhombic space group Pmn21 was reported with corresponding tilt system a 0 a 0 c +. It is argued here that such a structure is very implausible for a hydroxide perovskite. On heating sohngeite to 423 K, transformation to a cubic structure with $$Im\bar{3}$$ symmetry (a + a + a +) of the aristotype occurs. This cubic phase was recovered on cooling to 293 K without back-transformation to the tetragonal polymorph. As there is no continuous group/subgroup pathway from P42/nmc (or P42/n) to $$Im\bar{3}$$ , the transformation must be first-order, which is consistent with the large hysteresis observed. The change from the tetragonal to cubic structures involves a change in tilt system a + a + c − → a + a + a +, with a significant reconfiguration of hydrogen-bonding topology. The very different tilt systems and hydrogen-bonding configurations of the two polymorphs are responsible for hysteresis and metastable preservation of the cubic phase at 293 K. As the Ga(OH)6 octahedra of the low- and high-T polymorphs are very similar it is inferred that the transformation is driven by proton behaviour, presumably involving proton re-ordering.

Special Collection: Advances in Ultrahigh-Pressure Metamorphism: Tetrahedral boron in natural and synthetic HP/UHP tourmaline: Evidence from Raman spectroscopy, EMPA, and single-crystal XRD

Olenitic tourmaline with high amounts of tetrahedral B (up to 2.53 [4] B pfu) has been synthesized in a piston-cylinder press at 4.0 GPa, 700 °C, and a run duration of 9 days. Crystals are large enough (up to 30 × 150 μm) to allow for reliable and spatially resolved quantification of B by electron microprobe analysis (EMPA), single-crystal X-ray diffraction, and polarized single-crystal Raman spectroscopy. Tourmalines with radial acicular habit are zoned in [4] B-concentration [core: 2.53(25) [4] B pfu; rim: 1.43(15) [4] B pfu], whereas columnar crystals are chemically homogeneous [1.18(15) [4] B pfu]. An amount of 1.4(1) [4] B pfu was found in the columnar tourmaline by single-crystal structure refinement (SREF) ( R = 1.94%). The EMPA identify [T] Si −1 [V,W] O −1 [T] B 1 [V,W] (OH) 1 as the main and [X] □ −1 [T] Si −1 [X] Na 1 [T] B 1 as minor exchange vectors for [4] B-incorporation, which is supported by the SREF. Due to the restricted and well-defined variations in chemistry, Raman bands in the OH-stretching region (3000–3800 cm −1 ) are unambiguously assigned to a specific cation arrangement. We found the sum of the relative integrated intensity ( I rel ) of two low-frequency bands at 3284–3301 cm −1 (ν1) and 3367–3390 cm −1 (ν2) to positively correlate with the [4] B concentrations: [4] B [pfu] = 0.03(1) × [ I rel (ν1) + I rel (ν2)]. Hence, those bands correspond to configurations with mixed Si/B occupancy at the T site. Our semi-quantitative correlation also holds for well-characterized natural [4] B-bearing tourmaline from the Koralpe, Austria. This work shows the potential for Raman spectroscopy as a non-destructive method for the chemical classification of (precious) natural tourmaline, and as a tool to rapidly characterize chemical zonation of tourmalines in thin section.

High-pressure behavior and crystal–fluid interaction under extreme conditions in paulingite [PAU-topology

The compressional behavior and the P-induced crystal–fluid interaction of a natural paulingite-K have been explored on the basis of in-situ single-crystal and powder X-ray diffraction, and in-situ single-crystal Raman spectroscopy with a diamond anvil cell and a series of diverse pressure-transmitting fluids (i.e., silicone-oil, methanol:ethanol=4:1, methanol:ethanol:water=16:3:1). No evidence of any phase transition was observed within the P-range investigated, independent on the used P-fluids. The compressional behavior of paulingite is significantly different in response to the different nature of the P-fluids. A drastically lower compressibility is observed when the zeolite is compressed in methanol:ethanol or, even more noticeably, in methanol:ethanol:water mix. We ascribe this phenomenon to the different crystal–fluid interaction at high pressure: (1) silicone-oil is a “non-penetrating” P-medium, because of its polymeric nature, whereas (2) methanol–ethanol and water are “penetrating” P-fluids. The P-induced penetration processes appear to be completely reversible on the basis of the X-ray diffraction data alone. The Raman spectra collected after the high-pressure experiments show, unambiguously, that a residual fraction of methanol (and/or ethanol and probably even extra H2O) still resides in the zeolitic sub-nanocavities; such molecules are spontaneously released after a few days at atmospheric pressure. The actual compressibility of paulingite-K is that obtained by the compression experiment in silicone-oil, with an isothermal bulk modulus K0=β0−1=18.0(1.1)GPa. Paulingite appears to be one of the softest zeolite ever found.

The effects of pressure on structural strain in crystals with acetamide groups

Polymorphism is an ever growing area of interest in chemistry. Many active pharmaceutical ingredients (APIs) have the potential to have polymorphic forms, which can subsequently be used to the advantage of the pharmaceutical industry. There are a variety of conditions in which polymorphism can be examined; one way which has sparked interest in recent years is the influence of pressure and its effect on the behaviour of intermolecular bonds. The polymorphs of paracetamol were the first solid drugs for which the properties were compared at different pressures [1-2]. Another interesting research direction involves the comparison of the structural response to pressure of a series of chemically different compounds with similar molecular fragments, but possessing different molecular packing and intermolecular interactions. This is important for crystal engineering and for understanding structure-properties relationships. In the present study, we compare the response to pressure of a series of organic compounds with a common acetamide fragment: two polymorphs of paracetamol, two polymorphs of acetotoluidine, polymorphs and a hydrate of metacetamol, methacetin, and phenacetin. Both single-crystal Raman spectroscopy and X-ray diffraction were used. The effects of various pressure media have also undergone examination. The study was supported by the Year Abroad Programme of the University of Edinburgh (LM, CB), Russian Ministry of Science and Education and Russian Academy of Sciences (BAZ, SVG, EVB).

Crystal-chemical study of wavellite from Zbirov, Czech Republic

AbstractThe crystal chemistry of wavellite from Zbirov (Czech Republic), ideally Al3(PO4)2(OH,F)3·5H2O, was addressed by means of a multi-methodological approach based on electron microprobe analysis (EMPA) using wave-dispersive spectroscopy, single-crystal X-ray diffraction, powder and singlecrystal infrared spectroscopy and Raman spectroscopy. The EMPA data showed the presence of significant F replacing OH in the sample studied. The structure was solved in thePcmnorthorhombic space group, with the following unit-cell constants:a= 9.6422(7),b= 17.4146(15),c= 7.0094(2) Å,V= 1176.98(10) Å3. Phosphorus atoms display tetrahedral (PO4) coordination, while Al cations display octahedral coordination. The mineral framework can be viewed as the repetition of cationic arrays made up of AlO6polyhedra, bridged by PO4groups and further joined by O–H⋯O hydrogen bonds. The single-crystal unpolarized Fourier transform infrared (FTIR) spectrum shows combination bands indicating the presence of both OH and H2O in the structure. Both FTIR and Raman spectra show a broad absorption extending from 3600 to 2800 cm−1resulting from the overlapping of several components due to the water molecules and the OH group. The frequencies observed are comparable to those expected on the basis of the Libowitzky relationship for the range ofD–H⋯Abond systems in the structure.

Structural, Vibrational, Thermal, and Electrochemical Studies of a Cyclohexaphosphate Complex, (C5H14N2)2Cd2CL2P6O18.4H2O

A novel cadmium cyclohexaphosphate (C5H14N2)2Cd2Cl2P6O18.4H2O has been prepared and characterized by single-crystal X-ray diffraction, infrared and Raman spectroscopies, thermogravimetric analysis, and cyclic voltammetry. The structure consists of vertex linked of CdO5Cl octahedral and P6O18 rings assembled into a two-dimensional macroanionic layers. Organic double-protonated homopiperazine cations are located between these layers and interact with the framework both electrostatically and via hydrogen bonds of N–H···O(Cl). [Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the following free supplemental files: Additional figures]

Synthesis and characterization of 2CuCN·DMSO and [CuII(DMSO)6][CuI 6(CN)8] 3-D framework compounds

Abstract Two novel complexes of CuCN were characterized by using a single-crystal X-ray diffraction technique and Raman spectroscopy. In the structure of 2CuCN·DMSO ligand molecule demonstrates unique bridging mode, being bound to two CuI centers via oxygen and sulfur atoms. The bridging role of both CN groups and DMSO molecules results in the formation of (CuCN·DMSO)n framework. Along the channels of the network are running infinite zig-zag (CuCN)n chains, which are bound to the framework by elongated Cu…(CN) bonds. A mixed-valence [CuII(DMSO)6][CuI 6(CN)8] compound is composed of 3-D [CuI 6(CN)8]n anionic framework and located in the channels of partially disordered [CuII(DMSO)6]2+ cations.

Synthesis, Crystal Structure and Characterization of [(CH3 CH2)4N] Mn1,5 Cl3 4H2O Cl 2(H2O)

Single crystals of [(CH3CH2)4N] Mn1,5 Cl3 4H2O Cl 2(H2O) were grown by the slow evaporation technique and characterized by means of single-crystal X-ray diffraction, FT-IR and Raman spectroscopy. The title compound belongs to the triclinic space group P with the following unit cell dimensions: a =7.5425(4) Å, b=9.8464 Å, c=13.7671(6) Å, α=89.951(3)°,β=89.753(3)°, γ=81.861(3)°, Z=4. These structures have solved using direct methods and refined by least-squares analysis. The structure was solved by the direct method and refined to final R value of 0.0567. The projection of [(CH3CH2)4N] Mn1,5 Cl3 4H2O Cl 2(H2O) in the plan (a,b) shows an arrangement in layers perpendicular to the direction b . The structure consists of infinite parallel two-dimensional planes built connected ions and water molecules by strong O-H…O and O-H…Cl hydrogen bonding.

Single-crystal Raman spectroscopy of natural paulmooreite Pb2As2O5 in comparison with the synthesized analog

The single-crystal Raman spectra of the natural mineral paulmooreite Pb2As2O5 from the Langban, Filipstad district, Varmland province, Sweden, are presented for the first time. It is a monoclinic mineral containing an isolated [As2O5]4− dimer. Unpolarized single-crystal spectra of the natural and synthetic samples compare favorably with each other and are characterized by strong bands around 186 and 140 cm−1 and three medium bands at 800–700 cm−1. Band assignments were made based on band symmetry and spectral comparison between experimental band positions and those resulting from Hartree-Fock calculation of an isolated [As2O5]4− anion complex. Spectral comparison was also made with lead arsenites such as synthetic PbAs2O4 and Pb2(AsO2)3Cl and natural finnemanite to determine the contribution of the terminal and bridging O in paulmooreite. Bands at 760–733 cm−1 were assigned to terminal As-O vibrations, whereas stretches of the bridging O occur at 562 and 503 cm−1. The single-crystal spectra showed good mode separation, allowing bands to be assigned a symmetry species of A g or B g.

Multiple high-pressure phase transitions in BiFeO3

We investigate the high-pressure phase transitions in BiFeO3 by single crystal and powder x-ray diffraction, as well as single crystal Raman spectroscopy. Six phase transitions are reported in the 0-60 GPa range. At low pressures, up to 15 GPa, 4 transitions are evidenced at 4, 5, 7 and 11 GPa. In this range, the crystals display large unit cells and complex domain structures, which suggests a competition between complex tilt systems and possibly off-center cation displacements. The non polar Pnma phase remains stable over a large pressure range between 11 and 38 GPa, where the distortion (tilt angles) changes only little with pressure. The two high-pressure phase transitions at 38 and 48 GPa are marked by the occurence of larger unit cells and an increase of the distorsion away from the cubic parent perovskite cell. We find no evidence for a cubic phase at high pressure, nor indications that the structure tends to become cubic. The previously reported insulator-to-metal transition at 50 GPa appears to be symmetry breaking.

Experimental and theoretical study of the vibrational properties of diaspore (α-AlOOH)

Vibrational properties of diaspore, α-AlOOH, have been re-investigated using room-temperature single-crystal Raman spectroscopy and low-temperature powder infrared (IR) transmission spectroscopy. First-principles harmonic calculations based on density functional theory provide a convincing assignment of the major Raman peaks and infrared absorption bands. The large width of the Raman band related to OH stretching modes is ascribed to mode–mode anharmonic coupling due to medium-strength H-bonding. Additional broadening in the powder IR spectrum arises from depolarization effects in powder particles. The temperature dependence of the IR spectrum provides a further insight into the anharmonic properties of diaspore. Based on their frequency and temperature behavior, narrow absorption features at ~2,000 cm−1 and anti-resonance at ~2,966 cm−1 in the IR spectrum are interpreted as overtones of fundamental bending bands.

Single-crystal Raman spectroscopy and X-ray crystallography at beamline X26-C of the NSLS

Three-dimensional structures derived from X-ray diffraction of protein crystals provide a wealth of information. Features and interactions important for the function of macromolecules can be deduced and catalytic mechanisms postulated. Still, many questions can remain, for example regarding metal oxidation states and the interpretation of `mystery density', i.e. ambiguous or unknown features within the electron density maps, especially at ∼2 Å resolutions typical of most macromolecular structures. Beamline X26-C at the National Synchrotron Light Source (NSLS), Brookhaven National Laboratory (BNL), provides researchers with the opportunity to not only determine the atomic structure of their samples but also to explore the electronic and vibrational characteristics of the sample before, during and after X-ray diffraction data collection. When samples are maintained under cryo-conditions, an opportunity to promote and follow photochemical reactions in situ as a function of X-ray exposure is also provided. Plans are in place to further expand the capabilities at beamline X26-C and to develop beamlines at NSLS-II, currently under construction at BNL, which will provide users access to a wide array of complementary spectroscopic methods in addition to high-quality X-ray diffraction data.

Tris(hydroxypropyl)phosphine Oxide: A Chiral Three-Dimensional Material with Nonlinear Optical Properties

The achiral C_(3v) organic phosphine tris(hydroxypropyl)phosphine oxide (1) crystallizes in the unusual chiral hexagonal space group P6_3. The structure is highly ordered because each phosphine oxide moiety forms three hydrogen bonds with adjacent hydroxy groups from three different molecules. The properties of the crystals and the presence of hydrogen bonding interactions were investigated using single crystal Raman spectroscopy. The crystals show nonlinear optical properties and are capable of efficient second harmonic generation.

Crystal-chemical investigation of kalsilite from San Venanzo, Italy, using single-crystal X-ray diffraction and Raman spectroscopy

Crystal-chemical investigation of kalsilite from San Venanzo, Italy, using single-crystal X-ray diffraction and Raman spectroscopy

High-pressure X-ray and Raman study of a ferrian magnesian spodumene

The high-pressure behaviour of a synthetic P21/c ferrian magnesian spodumene, M2 (Li0.85Mg0.09Fe2+ 0.06)M1(Fe3+ 0.85Mg0.15)Si2O6, has been investigated using in situ single-crystal X-ray diffraction and Raman spectroscopy. No phase transition has been observed within the pressure range investigated. The isothermal equation of state up to 7 GPa was determined. V0, KT0 and K’, simultaneously refined with a Murnaghan equation of state, are: V0= 415.66(7) A3, KT0=83(1) GPa and K’=9.6(6). The magnitudes of the principal unit-strain coefficients were calculated and their ratios e1:e2:e3=1.00:1.85:2.81 at P=6.83 GPa indicate a very strong anisotropy. Monitoring of the intensity of b-type reflections (h+k= 2n+1) confirms that from room conditions up to 7 GPa the primitive lattice is maintained. Raman spectra have been collected up to 7.4 GPa. No change in the number of observed vibrational modes occurs in the pressure range investigated. At high frequency, the Raman doublet relative to the Si–O–Si vibrations of the two distinct tetrahedral chains is a broad band at room pressure, however, the frequency difference between the two modes increases with increasing pressure.

The dynamic properties of zircon studied by single-crystal X-ray diffraction and Raman spectroscopy

An investigation of the dynamic properties of synthetic non-metamict zircon, ZrSiO4, was undertaken using X-ray single-crystal diffraction and polarized single-crystal Raman spectroscopy. The X-ray results at room temperature show that the Zr cation located on the triangular dodecahedral site is tightly bonded. The atomic displacement parameters from different crystals and refinements on zircon are compared and shown to be different. This is probably a result of experimental problems associated with extinction and/or slight degrees of metamictization in natural samples. A calculation of the librational motions of the rigid SiO4 tetrahedron give a mean-square libration of 3.3(3) degree(2) along the a axes and 6.9(6) degree(2) along the c axis. The Raman spectrum shows some unusual features, such as the low wave number SiO4 bending Motion, upsilon (2), at 266 cm(-1), that can be explained by the structural properties of zircon. The structure is characterized by open 'channels' running parallel to [001] and they influence the energies of the SiO4 bending modes depending upon their symmetries. The Raman modes differ strongly in intensity and this can be explained by vibrational interactions with the electronic state of Zr4+. In contrast to garnet, which shares a few structural similarities with zircon, the Zr cation residing in the large dodecahedral site shows little dynamic disorder. In addition, all the external modes in zircon are harmonic in comparison to a few modes in pyrope garnet, for example, that soften with decreasing temperature.

Assignment of the structural OH stretching bands of gibbsite

Single-crystal Raman and FTIR methods have been combined to study the structural OH groups of gibbsite, Al(OH)3. According to factor group analysis, six unique OH stretching bands [ν (OH)] bands are expected to occur in both IR and Raman spectra. In this study, six ν(OH) bands were observed in both the Raman and IR spectra. Analysis of the gibbsite crystal structure reveals two distinct types of structural OH groups: interlayer and intralayer hydrogen-bonded OH groups. The ν(OH) bands corresponding to these two types of OH groups were clearly resolved using polarized single-crystal Raman spectroscopy. The interlayer hydrogen-bonded OH groups are oriented along the c axis of the crystal and are represented by three ν(OH) bands at 3433, 3370, and 3363 cm−1. In contrast, the intralayer hydrogen-bonded OH groups are oriented nearly parallel to the (001) face and are represented by the ν(OH) bands at 3623, 3526, and 3519 cm−1. Assignment of the ν(OH) bands was based, in part, upon the Lippincott and Schroeder one-dimensional (LS-1D) model of the hydrogen bond. Based upon the known geometry of each OH group, the LS-1D model was used to predict the ν(OH) frequencies corresponding to each OH group. Additional support for the band assignments was obtained by correlation between the single-crystal Raman band intensities and the OH bond orientations obtained from the crystal structure.

Single-crystal Raman spectroscopy study of dickite

Other| February 01, 1998 Single-crystal Raman spectroscopy study of dickite Clifford T. Johnston; Clifford T. Johnston Purdue University, Crop, Soil and Environmental Sciences, West Lafayette, IN, United States Search for other works by this author on: GSW Google Scholar Jozef Helsen; Jozef Helsen Search for other works by this author on: GSW Google Scholar Robert A. Schoonheydt; Robert A. Schoonheydt Search for other works by this author on: GSW Google Scholar David L. Bish; David L. Bish Search for other works by this author on: GSW Google Scholar Stephen F. Agnew Stephen F. Agnew Search for other works by this author on: GSW Google Scholar American Mineralogist (1998) 83 (1-2): 75–84. https://doi.org/10.2138/am-1998-1-208 Article history first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Clifford T. Johnston, Jozef Helsen, Robert A. Schoonheydt, David L. Bish, Stephen F. Agnew; Single-crystal Raman spectroscopy study of dickite. American Mineralogist 1998;; 83 (1-2): 75–84. doi: https://doi.org/10.2138/am-1998-1-208 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyAmerican Mineralogist Search Advanced Search Abstract Raman spectra were obtained from the (001), (010), and (100) faces of a St. Claire dickite specimen of known orientation. Raman spectra collected from the (010) and (100) faces of dickite are reported for the first time and reveal vibrational features significantly different from the (001) spectra. Variations in intensities of the v(OH) bands in polarized spectra were used to confirm previous band assignments, to determine the shape and orientation of the local Raman tensors for the OH1 and OH3 groups. The most striking polarization effect observed in the v(OH) region of dickite was the behavior of the a(c'c')a spectrum relative to Raman and IR spectra of other orientations. Unlike previously reported spectra, the dominant feature in this spectrum was the 3643 cm (super -1) band. This large increase in intensity of the 3643 cm (super -1) band in comparison with the other v(OH) bands was related to the fact that Raman spectra were recorded from the edge faces of dickite with the electric vector of the incident laser polarized along the c axis. This permitted observation of vibrational modes polarized along the c axis. Raman frequencies of the v(OH) bands assigned to the OH2 and OH4 groups differ from their IR counterparts by 12 cm (super -1) , suggesting that these groups may be related by a center of symmetry. For comparison, Raman spectra in the v(OH) region were also obtained from individual micro-crystals of kaolinite that were approximately 5 mu m across the (001) face. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Melting and premelting of silicates: Raman spectroscopy and X-ray diffraction of Li2SiO3 and Na2SiO3

The isostructural lithium (Li2SiO3) and sodium (Na2SiO3) metasilicates have been investigated from room temperature up to the melting point by single-crystal Raman spectroscopy and energy-dispersive X-ray powder diffraction. The unit-cell parameters and Raman frequencies of Li2SiO3 vary regularly with temperature up to the melting point, which is consistent with the lack of premelting effects in calorimetric measurements. In contrast, Na2SiO3 undergoes a transition at about 850 K from orthorhombic Cmc 21 symmetry, to a lower symmetry (possibly Pmc 21), and shows near 1200 K changes in the Raman spectra that correlate well with the premelting effects as determined from calorimetry observations. In both compounds, a high alkali mobility likely sets in several hundreds of degrees below the melting point. Premelting in Na2SiO3 is associated with extensive deformation of the silicate chains as evidenced near the melting point by similarities in the Raman spectra of the crystalline and liquid phases.

Single-Crystal Raman Spectroscopy of the Rubidium Alums RbM(III)(SO(4))(2).12H(2)O (M(III) = Al, Ga, In, Ti, V, Cr, Fe) between 275 and 1200 cm(-)(1): Correlation between the Electronic Structure of the Tervalent Cation and Structural Abnormalities.

Low-temperature single-crystal Raman spectra for RbM(III)(SO(4))(2).12H(2)O (M(III) = Al, Ga, In, Ti, V, Cr, Fe) and RbM(III)(SO(4))(2).12D(2)O (M(III) = Al, V) have been collected and assigned in the range 275-1200 cm(-)(1). These results permit classification of the Ti and V rubidium sulfate alums to the beta modification, whereas the remaining tervalent cations give the expected alpha modification. The dimorphism of the rubidium sulfate alums is explained in terms of the electronic structure of the tervalent cation, where the observation of the beta modification is associated with unequal occupancy of the t(2g) (O(h)()) orbitals. For the rubidium vanadium alums the (3)E(g) <-- (3)A(g) electronic Raman (eR) transition permits quantification of the trigonal field splitting of the t(2g) (O(h)()) orbitals (ca. 1940 cm(-)(1)). The profile of the eR band is sensitive both to changes in temperature and to deuteration. Analysis of the eR band profile suggests a reduced spin-orbit splitting of the (3)E(g) manifold, this being ascribed to excited state Jahn-Teller (J-T) effects. The similarity of the Raman spectra of the cesium and rubidium titanium sulfate alums suggest that they exhibit closely related structural chemistry, with both subject to phase transitions below 80 K. The observation that modes of E(g) symmetry are coupled to the structural change is consistent with the interpretation that the trigonal field leaves an orbital doublet ground term for titanium(III), leading to a cooperative J-T effect.