Performance with various diffraction gratings:

Outline Drawing In Progress

12-Hydroxy-1-azaperylene—Limiting Case of the ESIPT System: Enol–Keto Tautomerization in S0 and S1 States

Abstract: Absorption, fluorescence, and fluorescence excitation spectra of 12-hydroxy-1-azaperylene (HAP) and 1-azaperylene were studied in n-alkane matrices at 5 K. Two stable tautomers of HAP, each of them in n-nonane embedded in two sites, were identified and attributed to the enol and keto forms. Theoretical calculations of the energy and vibrational structure of the spectra suggest that tautomer A, with the (0, 0) transition energy at 18 980 ± 10 cm–1 (and 19 060 ± 10 cm–1 in the high energy site), should be identified as the keto form, whereas tautomer B, with the (0, 0) energy at 19 200 ± 20 cm–1 (19 290 ± 20 cm–1), as the enol form. Observation of absorption and fluorescence of both tautomeric forms and lack of large Stokes shift of fluorescence of the keto form classify HAP as the limiting case of the excited-state intramolecular proton transfer system.

Irena Deperasińska, Daniel T. Gryko, Elena Karpiuk, Bolesław Kozankiewicz, Artur Makarewicz, and Joanna Piechowska

Excited singlet state relaxation yields of pentacene in Shpol'skii matrices

Abstract: We studied absorption and fluorescence spectra and decays of pentacene (Pc) in Shpol'skii matrices of n-heptane (C7), n-nonane (C9), n-decane (C10), n-dodecane (C12), n-tetradecane (C14) and n-hexadecane (C16) in the temperature range 1.7–200 K. The fluorescence quantum yields of Pc in C12, C14 and C16 at 1.7 K were determined to be 20±6%, 26±6% and 22±6%, respectively. The kinetic analysis provided values of the radiative, internal conversion and intersystem crossing rate constants for the relaxation channels of the S1 state of Pc in different matrices. Calculated fully saturated emission rates of single molecule were in very good relation with previous observation of single Pc molecules in Shpol'skii matrices.

M. Banasiewicz, I. Deperasińska, D. Fabjanowicz, B. Kozankiewicz

Structural dynamics of 2,3-dimethylnaphthalene crystals revealed by fluorescence of single terrylene molecules

Abstract: Single terrylene molecules were detected for the first time in 2,3-dimethylnaphthalene crystals. Experiments provided information about the structural dynamics of the crystal over a wide temperature range. Blinking of the fluorescence intensity of terrylene molecules, between 5 and 150 K, was related to dynamics of the methyl groups of the host molecules surrounding the probe. Photo-bleaching of single terrylenes, monitored over the whole temperature range, at temperatures above 220 K was attributed to thermally activated reorientation of the host molecules, already discovered by nuclear magnetic resonance. Photo-bleaching time was too short to detect terrylene molecules at temperatures above 260 K.

M. Banasiewicz, D. Wiącek, B. Kozankiewicz

Ultraviolet photoluminescence from CuAlS2 heteroepitaxial layers grown by low‐pressure metalorganic chemical vapor deposition

Abstract: Photoluminescence(PL) studies were carried out on CuAlS2heteroepitaxial layers grown by low‐pressure metalorganic chemical vapor deposition. The epilayers exhibited an intense near‐band‐edge PL peak at 3.525 eV (77 K) in the ultraviolet (UV) wavelength region together with PL bands at 2.76 and 2.1 eV. This near‐band‐edge PL peak showed the following properties: (i) the PL was strongly polarized parallel to the c axis, (ii) the peak energy varied from 3.497 to 3.525 eV at 77 K with increasing epilayer thickness from 0.49 to 0.67 μm, and (iii) the emission was observed up to room temperature. This UV‐PL was tentatively assigned to an exciton‐related emission, energy shifted due to the residual lattice strain.

Shigefusa Chichibu, Hisayuki Nakanishi and Sho Shirakata

Spectroscopic diagnostics for liquid lithium divertor studies on National Spherical Torus Experiment

Abstract: The use of lithium-coated plasma facing components for plasma density control is studied in the National Spherical Torus Experiment (NSTX). A recently installed liquid lithiumdivertor (LLD) module has a porous molybdenum surface, separated by a stainless steel liner from a heated copper substrate. Lithium is deposited on the LLD from two evaporators. Two new spectroscopic diagnostics are installed to study the plasma surface interactions on the LLD: (1) A 20-element absolute extreme ultraviolet (AXUV) diode array with a 6 nm bandpass filter centered at 121.6 nm (the Lyman-α transition) for spatially resolved divertor recycling rate measurements in the highly reflective LLD environment, and (2) an ultraviolet-visible-near infrared R=0.67 m imaging Czerny–Turner spectrometer for spatially resolved divertor D I, Li I-II, C I-IV, Mo I, D2, LiD, CD emission and ion temperature on and around the LLD module. The use of photometrically calibrated measurements together with atomic physics factors enables studies of recycling and impurity particle fluxes as functions of LLD temperature, ion flux, and divertor geometry.

V. A. Soukhanovskii1, A. L. Roquemore, R. E. Bell, R. Kaita and H. W. Kugel

Wavelength calibration system of the grating monochrometer based on LabVIEW

Abstract: The new wavelength calibration system of the grating monochrometer was described to research the wavelength characteristic of Model 207 monochrometer which was used in the spectral responsivity measurement.The automatic parts of the facility were all connected with the computer by RS232 or IEEE-488.The wavelength calibration could be carried out automatically,and the monochrometer's performance was also tested.At last the method of processing acquisition data was introduced in the program.The experiment results show that the accuracy of the monochrometer wavelength is 0.02 nm.

Yang Jiajian, Lu Xiaofeng, Feng Xiaodong, Yuan Zundong

Development of soft plasma ionization (SPI) source for analysis of organic compounds

Abstract: We present a newly designed soft plasma ionization (SPI) source developed for mass spectrometric study of organic compounds in this study. The SPI cell having a relatively small size consists of a hollow anode and a hollow mesh cathode. The voltage–current characteristic depending on the pressure was investigated, indicating that it has similar characteristics to conventional hollow cathode glow discharges. To investigate the emission characteristics of the SPI source, some molecular band emission spectra (N2, N2+ and OH+) were measured by using argon and helium discharge gases. The SPI source was installed to a commercially used quadrupole mass analyzer for analyzing organic compounds. To demonstrate the SPI source, the mass spectra of some organic compounds (methylene chloride, toluene, benzene, cyclohexane and chloroform) were measured. The organic compounds were ionized with good stability in the plasma, and the fragmentation depended on the applied current. When helium and argon gases were used as the discharge gas, the helium plasma was more suitable for SPI-MS rather than argon because the argon plasma not only suffers from spectral interference but also has lower sensitivity.

Hyunkook Parka, Ickhee Leeb, Kyu Seong Choib, Kazuaki Wagatsumaa, Sang Chun Leeb