Selective Luminescence Spectroscopy of Poly(p-Phenylene) Thin Films at Room Temperature

1995 ◽  
Vol 413 ◽  
Author(s):  
M. A. Drobizhev ◽  
M. N. Sapozhnikov ◽  
V. M. KobryanskII
Keyword(s):  
Thin Films ◽  
Luminescence Spectrum ◽  
Room Temperature ◽  
Selective Excitation ◽  
Luminescence Spectroscopy ◽  
Luminescence Spectra ◽  
Model Calculations ◽  
Localization Threshold ◽  
Low Energy Tail ◽  
Room Temperature Luminescence

ABSTRACTSelectively excited room-temperature luminescence spectra are reported for thin films of poly(p-phenylene) (PPP) deposited onto quartz substrata. The spectra exhibit a localization threshold in the low-energy tail of the luminescence excitation band at vloc.= 22400 cm−1, 2200 cm−1 below the maximum of the excitation spectrum. Upon laser excitation at Vex < Vloc., the maximum Vem of the luminescence spectrum shifts linearly with Vex due to selective excitation of polymer segments. It was found that there exists the frequency range where the slope of the Vem vs Vex dependence is smaller than unity, which corresponds to our previous model calculations for the case of selective excitation of chromophores through broad phonon bands. At vex > vloc,, the luminescence spectrum is independent of Vex. This behavior can be explained if one assumes that upon excitation below the localization threshold the luminescence is related to polymer segments directly excited by laser, whereas upon exciting above the threshold the fast energy relaxation takes place from initially excited states to lower-lying states, from which uminescence occurs.

Investigations on the Rare Earth Terpyridyl System

1965 ◽  
Vol 20 (6) ◽  
pp. 835-837 ◽  
Author(s):  
Shyama P. Sinha
Keyword(s):  
Rare Earth ◽  
Room Temperature ◽  
Free Ligand ◽  
Ground Level ◽  
Phosphorescence Spectrum ◽  
Rare Earth Ions ◽  
Luminescence Spectra ◽  
Heterocyclic Ligands ◽  
Phosphorescence Lifetime ◽  
Room Temperature Luminescence

The room temperature luminescence spectra of the monoterpyridyl chelates of trivalent samarium, dysprosium and thulium have been studied in solid state by exciting with monochromatic radiation of 3200 Å. The spectra of these chelates show intra f → f fluorescent transitions of the chelated rare earth ions as well as the molecular band fluorescence. The “bottleneck” nature of the energy transfer from the nitrogen containing heterocyclic ligands to the coordinated rare earth ions is proposed. The fluorescence data of mono-terpyridyl chelates have been compared with those of bis-dipyridyl one.The phosphorescence spectrum of terpyridyl has also been investigated. The lowest triplet state of the free ligand is found at 22 940 cm-1 above the ground level. The phosphorescence lifetime of terpyridyl is about 2 sec

scholarly journals Структура R-=SUB=-1-=/SUB=- и R-=SUB=-2-=/SUB=- полос изотопов иона Cr-=SUP=-3+-=/SUP=- в монокристалле рубина при комнатной температуре

2021 ◽  
Vol 129 (4) ◽  
pp. 494
Author(s):  
В.С. Аракелян ◽  
Т.И. Бутаева ◽  
П.Г. Мужикян ◽  
Д.Г. Заргарян ◽  
Р.Б. Костанян
Keyword(s):  
Stable Isotopes ◽  
Comparative Analysis ◽  
Laser Diode ◽  
Room Temperature ◽  
Selective Excitation ◽  
Luminescence Spectra ◽  
Halogen Lamp ◽  
Combined Structure ◽  
Absorption And Luminescence Spectra ◽  
Excited Luminescence

Abstract. The absorption and luminescence spectra of the R1 and R2 bands in a ruby Al2O3:Cr3+ (0,05%) single crystal at room temperature were studied. The luminescence bands have been obtained both by excitation of the crystal by the radiation of a halogen lamp and by selective excitation of the two upper levels of the 2T1 state using the radiation of a laser diode with a tunable wavelength (656-662 nm). In the spectra of selectively excited luminescence bands, four different displacements of the R1 and R2 bands and four different distances between these bands have been detected, the change of which is a multiple of ~ 0.52 cm-1. A detailed comparative analysis of the obtained spectra of the luminescence bands and their absorption allowed us to determine the combined structure of each of the R1 and R2 bands, formed by additional doublets of these bands of all four stable isotopes of ions 50Cr3+, 52Cr3+, 53Cr3+ and 54Cr3+. The splitting of the obtained doublets varies from 7.04 to 9.14 cm-1 depend on the mass of the isotope

Emitting-state properties of square-planar dithiocarbamate complexes of palladium(II) and platinum(II) probed by pressure-dependent luminescence spectroscopy

2009 ◽  
Vol 87 (11) ◽  
pp. 1625-1635 ◽  
Author(s):  
Caroline Genre ◽  
Geneviève Levasseur-Thériault ◽  
Christian Reber
Keyword(s):  
Crystal Structure ◽  
Luminescence Band ◽  
Room Temperature ◽  
External Pressure ◽  
Luminescence Spectroscopy ◽  
Luminescence Spectra ◽  
Square Planar ◽  
Temperature And Pressure ◽  
Monodentate Ligands ◽  
Crystalline Complexes Of

Temperature- and pressure-dependent Raman and luminescence spectra of four crystalline complexes of palladium(II) and platinum(II) with chelating diethyldithiocarbamate (EDTC) and pyrrolidine-N-dithiocarbamate (PDTC) ligands are reported. The crystal structure of [Pd(PDTC)2] was resolved at 120 K. Luminescence band maxima are observed at approximately 14 500 cm–1 and 16 000 cm–1 for the palladium(II) and platinum(II) complexes, respectively. Pressure leads to blue shifts of the band maxima by +9 and +13 cm–1/kbar for [Pd(EDTC)2] and [Pd(PDTC)2], and +15 cm–1/kbar for [Pt(EDTC)2]. These spin-forbidden d–d luminescence transitions have lifetimes of approximately 600 µs at temperatures below 20 K. Luminescence intensities at room temperature are low, but they increase significantly with external pressure. The experimental results show that strong increases of luminescence intensities caused by pressure are not limited to complexes with monodentate ligands, a result providing insight on the coordinates with emitting-state distortions responsible for this effect.

Investigation of Coupling Mechanism between Erbium (Er3+) and Ytterbium (Yb3+) in Alumina (A12O3) Host

1999 ◽  
Vol 560 ◽  
Author(s):  
C.E. Chryssou ◽  
A.J. Kenyon ◽  
C.W. Pitt ◽  
P.J. Chandler ◽  
D.E. Hole
Keyword(s):  
Thin Films ◽  
Fluorescence Lifetime ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Luminescence Spectra ◽  
Coupling Mechanism ◽  
Alumina Matrix ◽  
Plasma Enhanced Cvd ◽  
Peak Intensity ◽  
Co Doped

ABSTRACTPlasma-enhanced CVD (PECVD) deposited alumina (A12O3) thin films and single sapphire crystals were co-doped with both erbium and ytterbium using ion implantation. Yb3+ and Er3+ concentrations ranged from 2.4At% to 8At% and from 0.4At% to 0.8At%, respectively. The samples show relatively strong, broad, room-temperature photoluminescence (PL) at λ=11.53µm corresponding to the intra-4f transitions between the 4I13/2 (first excited) and the 4I15/2 (ground) state of Er3+. The full width at half maximum (FWHM) of the emission spectrum is as high as 67nm for the A12O3 thin films; for the sapphire crystals it is 45nm. The fluorescence lifetime of the samples has been measured to be as high as 4.2ms at 50mW laser pump power. The indirect pumping of erbium through the transfer of energy from ytterbium has been demonstrated and the PL peak intensity has been studied as a function of the Yb3+/Er3+ concentration ratio when the samples are pumped at 514nm and 850nm; the PL excitation spectrum (PL at 1.53gm as a function of pump wavelength) of an Er3+/Yb3+ co-implanted sample is also presented. Both the PL peak intensity at 1.53µm and the fluorescence lifetime have been studied as functions of annealing temperature. Luminescence spectra attributed to defects in the alumina matrix are presented for as-implanted samples and following thermal annealing.

Recent Advances in the STM-based Luminescence Microscopy of Cu(In,Ga)Se2 thin films

2009 ◽  
Vol 1165 ◽  
Author(s):  
Manuel J. Romero ◽  
Miguel A. Contreras ◽  
Ingrid Repins ◽  
Chun-Sheng Jiang ◽  
Mowafak Al-Jassim
Keyword(s):  
Thin Films ◽  
Luminescence Spectrum ◽  
Electronic Properties ◽  
High Efficiency ◽  
Luminescence Spectroscopy ◽  
Scanning Tunneling ◽  
Luminescence Microscopy ◽  
Recent Advances ◽  
Spectrum Imaging ◽  
Tunneling Luminescence

AbstractWe report on recent advances in the development of a luminescence spectroscopy based on scanning tunneling microscopy (STM) and its application to fundamental aspects of Cu(In,Ga)Se2 (CIGS) thin films. Relevant to our discussion is the specifics of the surface electronics. The CIGS shows pronounced stoichiometric deviations at the surface and, consequently, distinct surface electronics that has been shown to be critical in achieving high efficiency. Cathodoluminescence (CL), a luminescence spectrum imaging mode in scanning electron microscopy (SEM), provides a direct correlation between the microstructure of the CIGS and its electronic properties. As such, cathodoluminescence can resolve the emission spectrum between grain boundaries and grain interiors or be used to investigate the influence of local orientation and stoichiometry on the electronic properties of the CIGS at the microscale. Cathodoluminescence is not a surface microscopy, however, and resolving the electronic structure of the CIGS surface remains elusive to all luminescence microscopies. With this motivation, we have developed a luminescence microscopy based on STM, in which tunneling electrons are responsible for the excitation of luminescence (scanning tunneling luminescence or STL). The hot-tunneling-electron excitation is confined to the surface and, consequently, the tunneling luminescence spectrum reveals the electronic states near the surface. The STM is integrated inside the SEM and, therefore, both CL and STL can be measured over the same location and compared. Using this setup, the transition from the grain interior to the surface can be investigated. We have improved the collection of our optics to a level in which tunneling luminescence spectrum imaging can be performed. Here we present a detailed account on our investigation of the surface electronics in CIGS deposited in the regime of selenium deficiency as defined by <Se>/(<Cu> + <In> + < Ga >) = 1.

Activation of Lead Fluoride Room Temperature Luminescence by Structural Modifications

1994 ◽  
Vol 348 ◽  
Author(s):  
D.L. Alov ◽  
A.V. Bazhenov ◽  
V.K. Egorov ◽  
G.A. Emelchenko ◽  
N.V. Klassen ◽  
...  
Keyword(s):  
Room Temperature ◽  
Structural Characteristics ◽  
Structural Defects ◽  
Luminescence Spectra ◽  
Lead Fluoride ◽  
Light Emitting ◽  
X Ray ◽  
Structural Modifications ◽  
Excited Luminescence ◽  
Room Temperature Luminescence

ABSTRACTThe connection of lead fluoride luminescence properties with its structural characteristics has been studied. Single crystals of the cubic and orthorombic phases, cubic and orthorombic powders, pressure compacted orthorombic ceramics, plastically deformed crystals were used. The photo- and X-ray excited luminescence spectra have been investigated. The experimental results have shown that the room temperature luminescence of lead fluoride can be accounted for local light emitting centers which are produced by the intrinsic structural defects in the orthorombic lead fluoride.

Laser-Excited Synchronous Luminescence Spectroscopy

1993 ◽  
Vol 47 (4) ◽  
pp. 430-435 ◽  
Author(s):  
Christopher L. Stevenson ◽  
Tuan Vo-Dinh
Keyword(s):  
Environmental Samples ◽  
Room Temperature ◽  
Laser System ◽  
Luminescence Spectroscopy ◽  
Multicomponent Mixtures ◽  
Convenient Means ◽  
Molecular Luminescence ◽  
Sensitivity And Selectivity ◽  
Synchronous Luminescence Spectroscopy ◽  
Room Temperature Luminescence

The use of lasers as excitation sources for molecular luminescence often results in improvements in sensitivity and limits of detection (LODs). Synchronous luminescence (SL) spectroscopy, in which both excitation and emission wavelengths are scanned simultaneously, provides a convenient means to improve selectivity (often dramatically) in the analysis of multicomponent mixtures using room-temperature luminescence. We report here on the first use of a dye laser as an excitation source for SL at room temperature. The performance of the laser synchronous luminescence (LSL) system is described for the analysis of four polyaromatic compounds; for one of these—tetracene—the LOD was 680 zeptomoles (10−21 mol) in the volume probed by the laser. In addition to impressive sensitivity and selectivity, the laser system used is quite small and can be considered as an attractive source for portable SL instruments designed for in-field screening of environmental samples.

Temperature- and pressure-dependent luminescence spectroscopy on the trans-[ReO2(pyridine)4]+ complex — Analysis of vibronic structure, luminescence energies, and bonding characteristics

2004 ◽  
Vol 82 (6) ◽  
pp. 1083-1091 ◽  
Author(s):  
John K Grey ◽  
Ian S Butler ◽  
Christian Reber
Keyword(s):  
Molecular Structure ◽  
Low Temperature ◽  
Room Temperature ◽  
Complex Analysis ◽  
Variable Pressure ◽  
Luminescence Spectroscopy ◽  
Luminescence Spectra ◽  
Vibronic Structure ◽  
Temperature Spectra ◽  
Temperature And Pressure

Resolved vibronic structure in electronic spectra provides a detailed view into how molecular structure changes after absorption or emission of a photon. We report temperature- and pressure-dependent luminescence spectra of trans-[ReO2(pyridine)4]I. Low-temperature spectra reveal long vibronic progressions in the totally symmetric O=Re=O (907 cm–1) and Re-pyridine (211 cm–1) stretching modes, indicating large structural displacements along these normal coordinates. The luminescence band maximum is at ca. 15 500 cm–1. Room-temperature spectra are somewhat less-resolved; however, intervals closely matching the O=Re=O frequency (~870 cm–1) persist at higher temperatures. The variable pressure spectra exhibit distinct changes in the vibronic patterns, and luminescence energies decrease by 16 ± 2 cm–1/kbar (1 bar = 100 kPa). Low-temperature spectra are modeled using two-dimensional potential energy surfaces to represent the initial and final electronic states, from which the quantitative normal coordinate offsets can be determined. We then adapt this model to the room-temperature, pressure-dependent data where it is possible to determine how the offsets and other important spectroscopic parameters vary with the pressure-induced changes of the molecular structure. Key words: trans-[ReO2(pyridine)4]I, low-temperature luminescence spectroscopy, high-pressure luminescence spectroscopy, vibronic structure, emitting state distortions.

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