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Articles 841 - 870 of 962

Full-Text Articles in Chemistry

Single Crystal Raman Spectra Of 1,2,4,5-Tetrabromobenzene: Calculational And Experimental Assignment Of The Internal Modes, K.M. White, Craig J. Eckhardt Jul 1998

Single Crystal Raman Spectra Of 1,2,4,5-Tetrabromobenzene: Calculational And Experimental Assignment Of The Internal Modes, K.M. White, Craig J. Eckhardt

Craig J. Eckhardt Publications

A detailed study of the fundamental internal modes of the 1,2,4,5-tetrabromobenzene crystal has provided assignments of Raman-active modes consistent with polarized single-crystal measurements. A normal-mode calculation based on a valence force field derived from brominated and chlorinated benzenes is found to be in excellent agreement with the assignments. Additional bands arising from anharmonic interactions of the fundamentals are also assigned.

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Structure And Lattice Dynamics Of Dipolarly Disordered 2,3-Dimethylanthracene Crystals, M. Dörr, H. Gerlach, J. Kalus, N. Karl, M. Monkenbusch, I. Natkaniec, U. Schmelzer, W. Schmidt, John J. Stezowski, P. Vorderwisch, M. Warth Jul 1998

Structure And Lattice Dynamics Of Dipolarly Disordered 2,3-Dimethylanthracene Crystals, M. Dörr, H. Gerlach, J. Kalus, N. Karl, M. Monkenbusch, I. Natkaniec, U. Schmelzer, W. Schmidt, John J. Stezowski, P. Vorderwisch, M. Warth

John J. Stezowski Publications

2,3-dimethylanthracene (2,3-DMA, C16H14) crystallizes in a pseudocentrosymmetric triclinic lattice with two molecules per unit cell showing dipolar structural disorder of the acentric molecules. Using powder samples the amplitude weighted phonon density of states was measured by inelastic incoherent neutron scattering for different degrees of deuteration. The differences in the resulting spectra can be explained by changes of the dynamics of the molecular bodies or the methyl side groups. By the method of inelastic coherent neutron scattering phonon dispersion curves were determined. The phonon lines are broad even at low temperatures; this fact is supposed to be …

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Contribution Of The Center-Of-Mass Fluctuation Of A Liquid Cluster To The Free Energy: A Monte Carlo Simulation Study, K.J. Oh, Xiao Cheng Zeng Mar 1998

Contribution Of The Center-Of-Mass Fluctuation Of A Liquid Cluster To The Free Energy: A Monte Carlo Simulation Study, K.J. Oh, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

The contribution of the center-of-mass (CM) fluctuation of a liquid cluster to the Helmholtz free energy was first discussed by Reiss, Katz, and Cohen (RKC). They argued that this contribution can be assessed via the free energy difference between the cluster with a fixed boundary centered on a fixed CM, and the cluster in which the CM was allowed to fluctuate. They estimated the free energy difference is to be about 20 kbT. Here kb is the Boltzmann constant and T is the temperature of the system. To examine this estimate, Abraham et al. later calculated …

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Method For The Synthesis Of Α-Oxranyl Amino Acids, David B. Berkowitz, Michelle L. Pedersen Jan 1998

Method For The Synthesis Of Α-Oxranyl Amino Acids, David B. Berkowitz, Michelle L. Pedersen

Department of Chemistry: Faculty Publications

The present invention is related to a novel class of decar-boxylase enzyme inhibitors consisting of α-oxiranyl amino acids and derivatives thereof and a method of synthesizing Such compounds.

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Pyrrolic Compounds, Michael J. Therien, Stephen Dimagno Jan 1998

Pyrrolic Compounds, Michael J. Therien, Stephen Dimagno

Department of Chemistry: Faculty Publications

Novel methylpyrroles are provided, as well as processes for their preparation.

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D/H Exchange In Nitro Diastereomers, Charles A. Kingsbury Jan 1998

D/H Exchange In Nitro Diastereomers, Charles A. Kingsbury

Department of Chemistry: Faculty Publications

The two diastereomers of 4-nitro-1,3-diphenylpentan-1-one behave differently in deuterium for hydrogen exchange in DMSO-d6/D2O solutions using various bases as catalyst. Reaction of the erythro diastereomer gives largely the same diastereomer upon D/H exchange (retention), i.e., exchange exceeds epimerization. Pyridine and acetonitrile as solvents lead to faster epimerization than exchange. In the threo diastereomer (DMSO-d6 solution), epimerization exceeds exchange, and the anion to some extent regains the same hydrogen originally removed by the base on the opposite face. 2-Bromo-4-nitro-1,3-diphenylbutan-1-one undergoes ring closure to the cyclopropane faster than exchange (within seconds). The cyclopropane shows faster exchange than equilibration, i.e., retention of configuration, …

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Metathesis-Based Synthesis Of Jasmonate And Homojasmonate Lactones, Candidates For Extracellular Quorum Sensing Molecules In Candida Albicans, Su C. Cho, Patrick Dussault, Amber D. Lisec, Ellen C. Jensen, Kenneth W. Nickerson Jan 1998

Metathesis-Based Synthesis Of Jasmonate And Homojasmonate Lactones, Candidates For Extracellular Quorum Sensing Molecules In Candida Albicans, Su C. Cho, Patrick Dussault, Amber D. Lisec, Ellen C. Jensen, Kenneth W. Nickerson

Department of Chemistry: Faculty Publications

Ring-closing metathesis of jasmonate esters is shown to provide a rapid entry to jasmonate lactones. The lactones were investigated as possible quorum sensing molecules for the fungi Candida albicans. Assays demonstrated no effect on fungal morphology at concentrations up to 96 mM.

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Substituted Polythiophenes From Highly Reactive Zinc Reagents, Reuben D. Rieke Jan 1998

Substituted Polythiophenes From Highly Reactive Zinc Reagents, Reuben D. Rieke

Department of Chemistry: Faculty Publications

A novel Zerovalent zinc species and an organozinc reagent are disclosed. The zerovalent zinc species is directly pro duced by reaction of a reducing agent on a zinc salt, preferably Zn(CN)2. The organozinc reagent results from the reaction of the zerovalent zinc species and an organic compound having one or more stable anionic leaving groups. These organozinc reagents include a wide spectrum of functional groups in the organic radical, and are useful in a variety of reactions schemes.

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Cross-Coupling Of Organic Compounds Using Cuprous Odide, Reuben D. Rieke Jan 1998

Cross-Coupling Of Organic Compounds Using Cuprous Odide, Reuben D. Rieke

Department of Chemistry: Faculty Publications

Cross-coupling or addition reactions of organic compounds, including acid halides, allylic halides, and C.B-unsaturated carbonyl containing compounds, with organozinc com pounds may be readily and Safely carried out in the presence of cuprous iodide. The use of this catalyst in the coupling reaction provides for the preparation of commercially useful products in the pharmaceutical, agrochemical and other industries.

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Freezing Of Confined Water: A Bilayer Ice Phase In Hydrophobic Nanopores, Kenichiro Koga, Xiao Cheng Zeng, Hideki Tanaka Dec 1997

Freezing Of Confined Water: A Bilayer Ice Phase In Hydrophobic Nanopores, Kenichiro Koga, Xiao Cheng Zeng, Hideki Tanaka

Xiao Cheng Zeng Publications

Molecular dynamics simulations were performed to study the phase behavior of a thin film of water confined to a slit nanopore with smooth walls. A first-order water-to-ice freezing transition has been observed. The resulting ice, which is a crystal of bilayer consisting of rows of distorted hexagons, does not resemble any ice crystals found so far. The confined water contracts upon freezing when the confinement load is low ( ∼0.5 kbar) and expands when the load is high (10 kbar). The residual entropy of the bilayer ice can be calculated exactly, which is about half of the entropy of the …

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Coordinate Regulation Of G- And C Strand Length During New Telomere Synthesis, Xinqing Fan, Carolyn Mary Price Nov 1997

Coordinate Regulation Of G- And C Strand Length During New Telomere Synthesis, Xinqing Fan, Carolyn Mary Price

Department of Chemistry: Faculty Publications

We have used the ciliate Euplotes to study the role of DNA polymerase in telomeric C strand synthesis. Euplotes provides a unique opportunity to study C strand synthesis without the complication of simultaneous DNA replication because millions of new telomeres are made at a stage in the life cycle when no general DNA replication takes place. Previously we showed that the C-strands of newly synthesized telomeres have a precisely controlled length while the G-strands are more heterogeneous. This finding suggested that, although synthesis of the G-strand (by telomerase) is the first step in telomere addition, a major regulatory step occurs …

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Langmuir Monolayers As Disordered Solids: Strain-State Calculations Applied To Stearic Acid, David R. Swanson, Tadeusz Luty, Craig J. Eckhardt Sep 1997

Langmuir Monolayers As Disordered Solids: Strain-State Calculations Applied To Stearic Acid, David R. Swanson, Tadeusz Luty, Craig J. Eckhardt

Craig J. Eckhardt Publications

This paper presents a calculational procedure to determine the equilibrium phase for a given surface pressure π. The monolayer is treated as orientationally free tails grafted to a two-dimensional net formed by the head groups of the amphiphilic molecules. The head groups form a subsystem with translational degrees of freedom characterized by strain variables in the plane of the surface, and the tail groups compose a subsystem characterized by rotational degrees of freedom. The order in the monolayer derives indirectly from the crystalline head groups through translational–rotational coupling. A stress–strain relation is derived which shows the energetically most favorable path …

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Scanning Motions Of An Atomic Force Microscope Tip In Water, Kenichiro Koga, Xiao Cheng Zeng Aug 1997

Scanning Motions Of An Atomic Force Microscope Tip In Water, Kenichiro Koga, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Integral equation techniques are used to study scanning motions of a single-atom tip of the atomic force microscope (AFM) over a rigid, hydrophobic monolayer substrate in water. The calculated force curve is found to be oscillatory, in agreement with recent AFM experiments, which can lead to multiple scanning trajectories for the tip under a constant load. The unique trajectory along which the system is thermodynamically stable is revealed. This study shows that the tip may take a hopping motion over a defect-free substrate due to layering of water molecules between the tip and substrate.

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Toward A Molecular Theory Of Vapor-Phase Nucleation. V. Self-Consistency In The Decoupled Dimer Limit, K.J. Oh, Xiao Cheng Zeng, H. Reiss Jul 1997

Toward A Molecular Theory Of Vapor-Phase Nucleation. V. Self-Consistency In The Decoupled Dimer Limit, K.J. Oh, Xiao Cheng Zeng, H. Reiss

Xiao Cheng Zeng Publications

The previous papers of this series introduced a molecular i / υ cluster theory of vapor phase nucleation. This theory differs from most conventional ones in that the cluster (due to fluctuation) is not only characterized by its number of particles i but also by a spherical volume υ. Thus the free energy of formation of the cluster is not merely a one-dimensional function of the number of particles i but a two-dimensional function of both i and v (i.e., it is a free energy surface). In the first stage of this development (Refs. 1–3) the theory is based on …

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Solvent-Induced Interactions Between Hydrophobic And Hydrophilic Polyatomic Sheets In Water And Hypothetical Nonpolar Water, Kenichiro Koga, Xiao Cheng Zeng, Hideki Tanaka Jun 1997

Solvent-Induced Interactions Between Hydrophobic And Hydrophilic Polyatomic Sheets In Water And Hypothetical Nonpolar Water, Kenichiro Koga, Xiao Cheng Zeng, Hideki Tanaka

Xiao Cheng Zeng Publications

Hydrophobic and hydrophilic interactions are two major intermolecular forces between hydrophobic nonpolar and hydrophilic polar sites of macromolecules or materials surfaces in solvents. To further understand these two interactions at the microscopic level, an idealized polyatomic model is devised, which includes hydrophobic, hydrophilic, and partially hydrophilic polyatomic planar square molecular sheets. The hydrophobic molecular sheet is composed of the Lennard-Jones particles while the hydrophilic molecular sheet consists of positive and negative charge sites. In the framework of the extended reference interaction site model integral equation theory the solvent-induced interactions (or the potential of mean forces) between two parallel molecular sheets …

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Thermal Decomposition Reactions Of Acetaldehyde And Acetone On Si(100), J.L. Armstrong, J.M. White, Marjorie Langell May 1997

Thermal Decomposition Reactions Of Acetaldehyde And Acetone On Si(100), J.L. Armstrong, J.M. White, Marjorie Langell

Marjorie A. Langell Publications

We have studied the thermal interactions of acetone and acetaldehyde on Si(100), both sputtered and annealed, using high resolution electron energy loss spectroscopy, (HREELS), x-ray photoelectron spectroscopy (XPS), and temperature programmed desorption (TPD). There is no carbonyl stretch in HREELS and the C and O(1s) XPS peaks reflect two different carbonyl processes, one involving bond cleavage, the other a reduction of the C–O bond order. Hydrogen TPD gives a peak at 840–850 K which is as much as threefold more intense than from H-saturated Si(100). SiO desorbs near 1050 K and XPS shows total loss of oxygen and …

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Vapor–Liquid Coexistence Of Quasi-Two-Dimensional Stockmayer Fluids, G.T. Gao, Xiao Cheng Zeng, Wenchuan Wang Feb 1997

Vapor–Liquid Coexistence Of Quasi-Two-Dimensional Stockmayer Fluids, G.T. Gao, Xiao Cheng Zeng, Wenchuan Wang

Xiao Cheng Zeng Publications

A quasi-two-dimensional (2D) Stockmayer model is developed in which the center of mass of the molecule is confined on a plane while the dipole of the molecule can rotate freely in three dimensional space. This model entails essential characteristics of systems such as dipolar molecules physisorbed on a solid surface, or a Langmuir monolayer consisting of short-chain molecules with a dipolar tail. The Gibbs ensemble Monte Carlo technique is employed to determine the vapor– liquid equilibria of the model fluids. An Ewald sum for this quasi-2D model is formulated to account for the long-range dipolar interactions. Three systems with different …

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Monte Carlo Simulation Of The Solid To Superliquid Phase Transition Of Langmuir Monolayers. Ii. Characteristics Of Phase Transition, M.D. Gibson, D.R. Swanson, Craig J. Eckhardt, Xiao Cheng Zeng Feb 1997

Monte Carlo Simulation Of The Solid To Superliquid Phase Transition Of Langmuir Monolayers. Ii. Characteristics Of Phase Transition, M.D. Gibson, D.R. Swanson, Craig J. Eckhardt, Xiao Cheng Zeng

Craig J. Eckhardt Publications

The restricted-to-free rotator phase transition of fatty acid monolayers has been modeled using a potential which represents the amphiphiles as planar cross sections of fourfold symmetry. Using much larger system sizes than paper I [D. R. Swanson, R. J. Hardy, and C. J. Eckhardt, J. Chem. Phys. 99, 8194 (1993)], Monte Carlo simulations of the isobaric–isothermal ensemble of model systems with varied number of objects were undertaken to study the effect of system size on the characteristics and order of the phase transition. A peak in the specific heat vs temperature curve was observed near the transition. For each system …

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Α-Vinyllysine And Α-Vinylarginine Are Time-Dependent Inhibitors Of Their Cognate Decarboxylases, David B. Berkowitz, Wan Jin Jahng, Michelle L. Pedersen Sep 1996

Α-Vinyllysine And Α-Vinylarginine Are Time-Dependent Inhibitors Of Their Cognate Decarboxylases, David B. Berkowitz, Wan Jin Jahng, Michelle L. Pedersen

Department of Chemistry: Faculty Publications

(±)-α-Vinyllysine and (±)-α-vinylarginine display time-dependent inhibition of L-lysine decarboxylase from B. cadaveris, and L-arginine decarboxylase from E. coli, respectively. A complete Kitz-Wilson analysis has been performed using a modification of the Palcic continuous UV assay for decarboxylase activity.

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Model Calculations Of Langmuir Monolayers: Pressure Effects On Tilting Behavior Of Idealized Amphiphiles, D.R. Swanson, Robert J. Hardy, Craig J. Eckhardt Jul 1996

Model Calculations Of Langmuir Monolayers: Pressure Effects On Tilting Behavior Of Idealized Amphiphiles, D.R. Swanson, Robert J. Hardy, Craig J. Eckhardt

Craig J. Eckhardt Publications

Model amphiphiles consisting of lines of Lennard-Jones (LJ) centers are investigated to determine the effect of pressure and molecular geometry on ground-state tilting behavior. Both the amphiphile length and the intramolecular distance between LJ centers is varied. The results give guidelines for understanding and controlling tilting behavior in monolayer films.

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Synthesis Of Higher Α-Chlorovinyl And Α-Bromovinyl Amino Acids: The Amino Protecting Group Determines The Reaction Course, David B. Berkowitz, Michelle L. Pedersen, Wan Jin Jahng Jun 1996

Synthesis Of Higher Α-Chlorovinyl And Α-Bromovinyl Amino Acids: The Amino Protecting Group Determines The Reaction Course, David B. Berkowitz, Michelle L. Pedersen, Wan Jin Jahng

Department of Chemistry: Faculty Publications

N-Trifluoroacetyl α-vinyl amino esters are smoothly converted to the corresponding α-chlorovinyl or α-bromovinyl amino esters through the agency of phenyselenyl chloride or phenylselenyl bromide, respectively, followed by oxidation and pyrolysis. Exclusively the (E)-extemal halovinyl isomer and the internal halovinyl isomer are observed. The amino protecting group is a critical determinant of the reaction course (alkene addition vs. 5-exo-trig-like cyclization).

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Epitaxial Growth Of Co3O3 On Coo(100), G.A. Carson, M.H. Nassir, Marjorie Langell May 1996

Epitaxial Growth Of Co3O3 On Coo(100), G.A. Carson, M.H. Nassir, Marjorie Langell

Marjorie A. Langell Publications

Under mildly oxidizing ultrahigh vacuum conditions, it is possible to form on top of CoO(100) single crystal substrates, thin films that have higher oxygen content but that preserve the overall symmetry of the CoO(100) low-energy electron diffraction pattern. X-ray photoelectron spectroscopy (XPS) and high-resolution electron-energy-loss spectroscopy (HREELS) data indicate that the epitaxial film grown on CoO(100) at 625 K and 531027 Torr is Co3O3-like in both oxygen content and XP/HREEL spectroscopic characteristics. Both materials are closest packed in lattice oxygen, with the mismatch of bulk O2-–O2- distances of approximately 5%. However, the Co …

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High Resolution Electron Energy Loss Spectroscopy Of Mno(100) And Oxidized Mno(100), Marjorie Langell, C.W. Hutchings, G.A. Carson , M.H. Nassir May 1996

High Resolution Electron Energy Loss Spectroscopy Of Mno(100) And Oxidized Mno(100), Marjorie Langell, C.W. Hutchings, G.A. Carson , M.H. Nassir

Marjorie A. Langell Publications

Single crystal MnO(100) substrates can be selectively oxidized to produce Mn2O3- and Mn3O4-like surfaces under mild oxidation/reduction conditions readily accessed under ultrahigh vacuum (UHV). MnO(100) yields a characteristic Mn 2p x-ray photoelectron spectroscopy (XPS) satellite structure and appropriate O/Mn concentrations from O 1s/Mn 2p XPS intensity ratios. Its high resolution electron energy loss (HREEL) spectrum shows a series of Fuchs–Kliewer multiple phonon excitations with a single loss energy of 70.9 meV, characteristic of the cubic manganese monoxide structure. However, the HREEL spectral (HREELS) background is high and the …

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Thermal Nucleation And Cavitation In Helium-3 Fluids, Xiao Cheng Zeng, D.W. Oxtoby, E. Cheng Mar 1996

Thermal Nucleation And Cavitation In Helium-3 Fluids, Xiao Cheng Zeng, D.W. Oxtoby, E. Cheng

Xiao Cheng Zeng Publications

We have investigated droplet nucleation and bubble cavitation in the quantum fluid helium-3 based on a nonlocal density-functional approach. A marked effect of droplet (or bubble) curvature on the rate of droplet nucleation or cavitation has been found. Without considering this curvature effect (as in the classical theory of nucleation) the droplet nucleation rate for helium-3 could be underestimated (i.e., near 1 K) or overestimated (i.e., near 2.5 K) by orders of magnitude, respectively; for bubble cavitation, the rate could be underestimated by more than twenty orders of magnitude (near 1 K).

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Gas–Liquid Nucleation In Two-Dimensional Fluids, Xiao Cheng Zeng Feb 1996

Gas–Liquid Nucleation In Two-Dimensional Fluids, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

A nonclassical theory of nucleation, based on the density-functional (DF) approach, is developed for the gas–liquid transitions of two-dimensional (2D) Lennard-Jones (LJ) fluids. The methods of Weeks–Chandler–Andersen perturbation theory are used to approximate the LJ potential with a temperature-dependent hard-disk diameter plus an attractive tail. The resulting free energy functional is then used to calculate the free energy barrier to nucleation. We find that the curvature of the 2D nucleus is not important to the rate of nucleation (in contrast to the 3D counterpart). The effect of curvature is readily inferred from the ratio of nucleation rate from classical Becker–Dö̈ring …

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Highly Reactive Form Of Copper And Reagents Thereof, Reuben D. Rieke Jan 1996

Highly Reactive Form Of Copper And Reagents Thereof, Reuben D. Rieke

Department of Chemistry: Faculty Publications

A novel Zerovalent copper species and an organocopper reagent are disclosed. The Zerovalent copper species is directly produced by reaction of a reducing agent with a combination of copper(I) cyanide or halide and an alkali metal halide salt. The organocopper reagent resulting from the reaction of the zerovalent copper species and an organic compound having one or more stable anionic leaving groups is a stable reagent that will not significantly homocouple and under controlled conditions tolerates the presence of nitrile, epoxide, imine, enone, ketone, ester, allyl and benzyl groups within the organo radical. The reagent can be controlled so that …

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A Convenient Synthesis Of L-Α-Vinylglycine From L-Homoserine Lactone, David B. Berkowitz, Marianne K. Smith Jan 1996

A Convenient Synthesis Of L-Α-Vinylglycine From L-Homoserine Lactone, David B. Berkowitz, Marianne K. Smith

David Berkowitz Publications

A procedure for the synthesis ofL-IX-vinylglycine from L-homoserine lactone is described. The route developed is convenient (only one chromatography step is required) and efficient (72 %; ≥ 95 % optical yield over 4 steps). Key features include the use of acid-labile protecting groups for the amino (Boc) and carboxyl (diphenylmethyl ester) groups, and the use of the phenylselenolate equivalent derived from sodium borohydride and diphenyl diselenide for L-homoserine lactone cleavage.

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Highly Reactive Zerovalent Metals From Metal Cyanides, Reuben D. Rieke Jan 1996

Highly Reactive Zerovalent Metals From Metal Cyanides, Reuben D. Rieke

Department of Chemistry: Faculty Publications

Novel zerovalent metal species and organometallic reagents are disclosed. The zerovalent metal species are directly produced by reaction of a reducing agent on a metal cyanide salt. Preferably, the zerovalent metal species are directly produced by reaction of an alkali metal reducing agent with a metal cyanide salt. The organometallic reagent results from the reaction of the zerovalent metal species and an organic compound having one or more stable anionic leaving groups.

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Reply To ‘‘Comment On ‘Brillouin-Scattering Study Of The Elastic Constants Of Phenothiazine Through The Phase Transition’ ’’, J. Sartwell, Craig J. Eckhardt Oct 1995

Reply To ‘‘Comment On ‘Brillouin-Scattering Study Of The Elastic Constants Of Phenothiazine Through The Phase Transition’ ’’, J. Sartwell, Craig J. Eckhardt

Craig J. Eckhardt Publications

Disagreement in the ordering of relative magnitudes of the elastic constants of phenothiazine with those of Ecolivet et al. is resolved. Dubious methodologies and assumptions employed by Ecolivet et al. in their measurements, approximations, and arguments [C. Ecolivet et al., Phys. Rev. B 44, 4185 (1991)] are noted. Samples employed by these investigators in both their ultrasonic and Brillouin measurements are shown to exhibit properties consistent with impure samples and inconsistent with those of Sartwell and Eckhardt.

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Anisotropic Anharmonicity Of Lattice And Molecular Vibrations Of 1,2,4,5 Tetrabromobenzene Determined By Piezomodulated Raman Spectroscopy, K.M. White, Craig J. Eckhardt Sep 1995

Anisotropic Anharmonicity Of Lattice And Molecular Vibrations Of 1,2,4,5 Tetrabromobenzene Determined By Piezomodulated Raman Spectroscopy, K.M. White, Craig J. Eckhardt

Craig J. Eckhardt Publications

Strain-induced coupling constants for the anharmonicity of Raman-active lattice and certain molecular modes of vibration in 1,2,4,5-tetrabromobenzene (TBB) crystals have been determined using piezomodulated Raman spectroscopy. These constants, which are directly related to the first anharmonic term in the potential energy expansion for lattice dynamical calculations, are a quantitative measurement of the modal anharmonicities in the TBB molecular crystal. Application of uniaxial stress in the experiments permits the anisotropy of the anharmonicity to be determined as well as its magnitude. The TBB lattice modes are significantly coupled by the induced strains and the effects of coupling were observed to be …

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