Louis J. Basile

Effect of Styrene Monomer on the Fluorescence Properties of Polystyrene

Fluorescence spectra and lifetimes have been studied for polystyrene samples having different average molecular weights and different concentrations of residual styrene monomer. The residual styrene monomer is fluorescent and acts as a typical fluorescent solute in a rigid medium. The fluorescence properties of polystyrene were found to be dependent on both the concentration of residual styrene monomer and, to a lesser extent, the average molecular weight.

Spectroscopy at High Pressures—Status Report and Update of Instrumental Techniques

A status report and update of the instrumentation necessary to obtain spectra of molecules at high pressures are presented. The optical pressure cells used, the spectrophotometer needed to obtain the spectra, the optical link between the two, high pressure spectroscopic windows, pressure calibration methods, and future outlook of the technique will be determined. The use of the high pressure cells with the interferometric technique and for Raman spectroscopy is outlined.

The Raman scattering of uranyl and transuranium V, VI, and VII ions

The Raman scattering of U(VI), Np(VI), Pu(VI), Am(VI), and Np(V), Am(V) in HClO4 solutions and Np(VII) in a NaOH medium is reported. Direct observation of the polarized ν1 vibration (D∞h symmetry) is observed for the transuranium MO2n+ ions in the V and VI oxidation states. The spectroscopic evidence is consistent with a linear MO2n+ structure for the Np(VII) ion in basic solutions. The trend of the ν1 frequency and the MO stretching force constants with the oxidation is discussed and is correlated with the bond strengths and the stability of the MO2n+ ions.

Effects of temperature and pressure on the molecular and electronic structure of N,N′-ethylenebis(salicylideneiminato)nitrosyliron, Fe(NO)(salen)

Abstract The crystal and molecular structures of the two magnetically distinct forms of Fe(NO)(salen), C 16 H 14 N 3 O 3 Fe, have been determined by single crystal X-ray diffraction at 23 °C and at −175 °C. The complex crystallizes in the orthorhombic space group Pna2 1 with 4 molecules per unit cell. The unit cell dimensions are a = 26.377(2), b = 8.598(5) and c = 6.951(5) A at 23 °C and a = 26.18(2), b = 8.52(1) and c = 6.783(6) A at −175 °C. Full-matrix least-squares refinement of the 23 °C structure based on the 840 reflections with F 2 o ⩾ 3σ(F 2 o ) gave a conventional R-factor of 0.038. The structure consists of discrete Fe(NO)(salen) molecules with tetragonal pyramidal coordination about the iron atom. The disordered nitrosyl group occupies the axial coordination site in a bent geometry (average FeNO angle 147°). Full-matrix least-squares refinement of the −175°C structure based on the 406 reflections with F 2 o ⩾ 2σ(F 2 o ) gave a conventional R-factor of 0.087. This form of Fe(NO)(salen) also exhibits tetragonal pyramidal coordination geometry with a bent disordered nitrosyl group in the apical position. Marginally significant structural changes are observed: 1) the FeNO angle is 127°; 2) the Fe atom is 0.1 A closer to the mean coordination plane of the salen ligand are more nearly coplanar. These structural changes are consistent with a spin state of Fe(NO)(salen) from S = 3 2 to S = 1 2 upon cooling. The significant differences in th conformations of the salen ligand at the two temperatures are attributed to crystal packing. The infrared spectra of Fe(NO)(salen) at room temperature for various pressures ranging from ambient pressure up to 37 kbar are reported. The spectra suggest that Fe(NO)(salen) is converted to the S = 1 2 state at high pressure.

The hydrated proton H+(H2O)n. II. A spectroscopic study and normal coordinate treatment of the oxonium ions H3O+ and D3O+

A spectroscopic study and a normal coordinate treatment (NCT) of the oxonium ions H3O+ and D3O+ in solid H3O+CH3C6H4SO3− and D3O+CH3C6H4SO3− were made. Neutron diffraction studies indicated a pyramidal, C3ν symmetry for the oxonium ions. Based on this symmetry, the observed frequencies for H3O+ and D3O+ were assigned and a NCT attempted using the general valence force field and the Urey‐Bradley force field. Comparison of the fundamental vibrations in various oxonium compounds was made. It was demonstrated that a relationship between the OH stretching frequencies in H3O+ and D3O+ ions vs R (the O⋯O distance) exists, as well as a relationship between the stretching frequency shift (Δνs) and R. The failure of past investigators to recognize this trend may have contributed to the confusion regarding the assignments. This is the first confirmation of such a trend existing in oxonium compounds. It is suggested that the stretching mode frequencies in H3O+ and D3O+ are dependent on R. When Rx‐y is greater than th...

Characteristics of Plastic Scintillators

Information on the light output of a group of organic solutes in polyvinyltoluene has been obtained. The primary solutes studied are p‐terphenyl and 2‐phenyl‐5‐(4‐biphenylyl)‐1,3,4 oxadiazole (PBD), the latter being the most efficient. Of the secondary solutes studied, 4,4′‐diphenylstilbene and 2,5‐dibiphenylyl oxazole (BBO) are the most efficient. The best plastic scintillator developed contains a combination of 2‐phenyl‐5‐(4‐biphenylyl)‐1,3,4 oxadiazole (PBD) and 4,4′‐diphenylstilbene.The fluorescence spectra of these plastic scintillators were determined. When a secondary solute is added to a plastic scintillator the emitted light is mainly that of the secondary solute.The effect on the light output of the plastic scintillator upon addition of diphenylmercury was also investigated. Regardless of which combination of solutes was used, the mercury compound proved to be a serious quencher of light output.

I.R. spectra of several lanthanide oxyhalides

Abstract The i.r. spectra of several lanthanide oxychlorides and oxybromides have been measured. On the basis of a tetragonal D4h7 space group (Z=2), 15 total optical mode fundamentals can be predicted from the selection rules and consist of the following species: 2A 1g +2A 2u +3E g +2E u +1B 1g where the gerade (g) vibrations are Raman active and the ungerade (u) vibrations are i.r. active. Comparison of the infrared spectra with the Raman spectra of some of these compounds illustrates a lack of coincidences as predicted from the above space group. The spectroscopic results appear to be consistent with the above selection rules.

A Study of Na2O-TiO2-SiO2 Glasses by Infrared Spectroscopy

The infrared absorption spectra of six Na2O-TiO2-SiO2 glasses in the frequency range of 1600 to 200 cm−1 are reported. These glasses, having a SiO2/Na2O molar ratio of 1.07 to 3.54, and containing 20 or 25 mole % TiO2, demonstrate two main absorptions at ∼950 cm−1 and at ∼450 cm−1. A weak absorption at ∼790 cm−1 becomes progressively weaker in intensity, and a weak shoulder at 1050 cm−1 appears with increasing Na2O content. The frequency of the absorption band at ∼950 cm−1 is found to decrease markedly and systematically with a decrease in the SiO2/Na2O molar ratio, whereas the frequency of the band at ∼450cm−1 shows a slight increase. The infrared results may be interpreted in terms of a lowering of symmetry occurring for the SiO4 units. The effect of TiO2 content on the relationship between vibrational frequency is discussed. The frequency composition curves for glasses containing 20 and 25 mole % of TiO2 intersect at SiO2/Na2O ratio ∼2. A reversal in the frequency vs SiO2/Na2O ratio relation was also found at SiO2/Na2O ∼2 for the sodium silicate glasses.

The reaction of fluoroxysulfate, sof-. liith aromatic compounds: catalysis by acids

Abstract The effects of the acid catalysts HF, H 2 S0 4 , BF 3 , CF 3 S0 3 H, FSO 3 H, and SbF 5 .FS0 3 H on the reactions of CsSO 4 F with toluene, nitrobenzene and naphthalene in CH 3 CN have been studied. The catalys general accelerate reaction and enhance yields of ring-fluorinated products. Efficacity roughly parallels H 0 of the acids, though H 2 S0 4 is more effective than stronger acids for the fluorination of naphthalene. Combined room temperature yields of fluorine-substituted products are as much as 45-50% for toluene and naphthalene and up to 30% for nitrobenzene. The predominant products are o-fluorotoluene, 1- fluoronaphthalene, and m-fluoronitrobenzene. With naphthalene the isomer selectivity is considerably less than in the absence of catalyst. Low yields (10%) of monomeric oxygenated products are obtained, along with considerable oxygen- and fluorine-containing dimers and higher polymers. The results are interpreted in terms of acid-catalyzed electrophilic fluorination or oxygenation, followed by further fluorination and/or free-radical-induced oxidative coupling of the oxygenated products.

Transfer of Excitation Energy in Solid Solutions of Anthracene‐Polystyrene and 9,10‐Diphenylanthracene‐Polystyrene

The transfer of excitation energy from the excited solvent to the solute has been studied as a function of solute concentration for solid solutions of anthracene and 9,10‐diphenylanthracene in polystyrene. Transfer efficiencies and fluorescence spectra have been obtained for both systems. The fluorescent light pulse of both systems, when excited by electrons and uv radiation, was recorded and analyzed. Results indicate that radiative transfer predominates at low solute concentration, while at higher solute concentration the transfer process is predominantly nonradiative. Differences between the two systems are probably due to anthracene being chemically bound to the polymer chain while 9,10‐diphenylanthracene is not.