Normal coordinate calculations of benzenoid hydrocarbons: Classification and characterization of Aromatic planar vibrations in polyacenes

Classification methods for aromatic planar vibrations are presented. These methods involve the potential energy distribution analysis and a ring motion analysis, which makes it possible to classify collective motions of CC bonds in these systems into certain typical patterns. The planar vibrations of benzene and polyacenes up to pentacene are classified in this way, and the characteristic vibrations of these molecules are so described and analyzed. Normal coordinate calculations of naphthacene and pentacene have been carried out to illustrate the classification, and results were found to be very satisfactory.     

Determination of sulphide ion at trace levels by ethylation and gas chromatography

Summary A method is described for the determination of sulphide ion in aqueous samples by gas chromatography. Sulphide is ethylated with diethyl sulphate and the resulting diethyl sulphide is extracted with chloroform and determined with a gas chromatograph equipped with a flame ionization or a flame photometric detector. In the case of a flame photometric detector, the detection limit for sulphide ion is 0.05 g/ml. Other anions commonly found with sulphide ion do not interfere. Sulphide ion in spring waters was analysed by this new method and for comparison also by colorimetry (methylene blue). The results revealed the reliability of the new method.

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Bestimmung von Sulfidspuren durch Ethylierung und Gas-Chromatographie

Zusammenfassung Sulfid wird mit Diethylsulfat ethyliert, das gebildete Diethylsulfid mit Chloroform extrahiert und gaschromatographisch mit Hilfe eines Flammenionisationsoder eines flammenphotometrischen Detektors bestimmt. Die Nachweisgrenze beträgt 0,05 g S/ml für den FPD. Anionen, die üblicherweise mit Sulfid zusammen vorkommen, stören nicht. Das Verfahren wurde, im Vergleich mit der colorimetrischen Methylenblaumethode, auf Quellwasser angewendet. Es wurde gute Übereinstimmung der Ergebnisse erzielt.

     

Infrared-microwave double resonance of propynal by using the 3.51 μm HeXe laser

The 3.51 μm HeXe laser is magnetically tuned over a wavenumber of 0.2 cm^?1 and used for infrared absorption and double resonance spectroscopy. Eight rotation-vibration lines of propynal in the ν₂ band are assigned by the Stark effect. Eleven microwave transitions in the v₂ = 1 vibrational state are observed by the method of infrared-microwave double resonance. The rotational constants of the excited state and the band origin of the vibration ν₂ are determined from the observed spectra.     

Optically detected electron—nuclear double resonance and electron—nuclear—nuclear triple resonance study of 17O hyperfine coupling in the lowest nπ* triplet state of benzil

Optically detected ENDOR and electron—nuclear—nuclear triple resonance of ¹⁷O were measured via phosphorescence from ³(nπ^*) benzil in benzophenone-d₁₀ crystals at high magnetic field. The n and π^* spin densities on the oxygen atom are 0.201 and 0.092, respectively, the angle between the two CO bonds being 150°.     

Glueball mass estimate by strong coupling expansion in lattice gauge theories

In the formalism presented in the previous paper, the plaquette-plaquette correlation functions in arbitrary directions are calculated for Z(2), SU(2) and SU(3) up to order g^?8. Approximate restoration of rotational symmetry is observed in the continuum limit for SU(2), but much higher order corrections seem to be required in order to restore the symmetry for SU(3). The scalar glueball mass deduced from the plaquette-plaquette correlation function in the diagonal direction is 0.80 GeV, while the on-axis computation up to order g^?16 predicts it to be 0.64 GeV.     

A digitally controlled diode-laser spectrometer: Infrared spectrum of the ν4 band of acetonitrile between 890 and 960 cm−1

The ν₄ vibration-rotation spectrum of acetonitrile (CH₃CN) has been measured using a newly constructed diode-laser spectrometer controlled digitally by a microprocessor. The spectrum was observed in the range between 890 and 960 cm^?1 with Doppler-limited resolution. The P and R branches of the ν₄ fundamental band have been assigned up to K = 9. A small anomaly found in the high K lines is being explained by an anharmonic resonance with the v₈ = 3³ state. The determined interaction constant is small, but significant.     

Quantum mechanical single-gold-nanocluster electroluminescent light source at room temperature

Electrically contacted gold-nanocluster arrays formed within electromigration-induced break junctions exhibit bright, field-dependent electroluminescence in the near infrared (650-800 nm). Intensity autocorrelation of spatially isolated individual nanocluster emission driven at high electrical frequency (f(ac)= approximately 200 MHz) reveals antibunched electroluminescence at room temperature. These results demonstrate the single quantum nature of several-atom gold molecules and suggest their use as room-temperature electrically driven single-photon sources.     

30-mJ, diode-pumped, chirped-pulse Yb:YLF regenerative amplifier

A diode-pumped chirped-pulse regenerative amplifier with a cooled Yb:YLF crystal has been developed. The output pulse energy is 30 mJ at 20-Hz repetition rate. A high effective extraction efficiency of 68% is obtained, which is attributed to reduced saturation fluence at low temperature and to a high effective pulse energy fluence during regenerative amplification. After pulse compression by use of a parallel grating pair, 18-mJ pulse energy and 795-fs pulse duration are obtained.     

Local structures in ionic liquids probed and characterized by microscopic thermal diffusion monitored with picosecond time-resolved Raman spectroscopy

Vibrational cooling rate of the first excited singlet (S(1)) state of trans-stilbene and bulk thermal diffusivity are measured for seven room temperature ionic liquids, C(2)mimTf(2)N, C(4)mimTf(2)N, C(4)mimPF(6), C(5)mimTf(2)N, C(6)mimTf(2)N, C(8)mimTf(2)N, and bmpyTf(2)N. Vibrational cooling rate measured with picosecond time-resolved Raman spectroscopy reflects solute-solvent and solvent-solvent energy transfer in a microscopic solvent environment. Thermal diffusivity measured with the transient grating method indicates macroscopic heat conduction capability. Vibrational cooling rate of S(1) trans-stilbene is known to have a good correlation with bulk thermal diffusivity in ordinary molecular liquids. In the seven ionic liquids studied, however, vibrational cooling rate shows no correlation with thermal diffusivity; the observed rates are similar (0.082 to 0.12 ps(-1) in the seven ionic liquids and 0.08 to 0.14 ps(-1) in molecular liquids) despite large differences in thermal diffusivity (5.4-7.5 × 10(-8) m(2) s(-1) in ionic liquids and 8.0-10 × 10(-8) m(2) s(-1) in molecular liquids). This finding is consistent with our working hypothesis that there are local structures characteristically formed in ionic liquids. Vibrational cooling rate is determined by energy transfer among solvent ions in a local structure, while macroscopic thermal diffusion is controlled by heat transfer over boundaries of local structures. By using "local" thermal diffusivity, we are able to simulate the vibrational cooling kinetics observed in ionic liquids with a model assuming thermal diffusion in continuous media. The lower limit of the size of local structure is estimated with vibrational cooling process observed with and without the excess energy. A quantitative discussion with a numerical simulation shows that the diameter of local structure is larger than 10 nm. If we combine this lower limit, 10 nm, with the upper limit, 100 nm, which is estimated from the transparency (no light scattering) of ionic liquids, an order of magnitude estimate of local structure is obtained as 10 nm < L < 100 nm, where L is the length or the diameter of the domain of local structure.