scholarly journals Multiphoton Dissociation of Phenylsilane Upon Excitation at 212.5 NM

1996 ◽  
Vol 16 (3) ◽  
pp. 157-166 ◽  
Author(s):  
Mohamed Oujja ◽  
Margarita Martín ◽  
Rebeca De Nalda ◽  
Marta Castillejo
Keyword(s):  
Internal Energy ◽  
Excited States ◽  
Fluorescence Spectra ◽  
Narrow Band ◽  
Energy Content ◽  
Laser Energy ◽  
Emission Spectra ◽  
Molecular Fragments ◽  
Multiphoton Dissociation ◽  
Nm Range

The photodissociation processes that follow the photolysis of phenylsilane with a narrow band laser at 212.5 nm were studied by observing photofragment fluorescence spectra in the 200 to 900 nm range. Emission from several excited states of Si atoms was detected together with emissions from the molecular fragments SiH(A2∆) and C2(d3∏g). Si and SiH emissions show a quadratic dependence with laser energy whereas dependence for C2 emission is cubic, indicating the participation of two and three photon processes in the formation of the respective fragments. The emission spectra of the molecular fragments provides information about their internal energy content and allows discussion of the possible channels responsible for the appearance of those fragments.

Characterization of Amethysts from Sukamara, Central Kalimantan, Using Laser-Induced Breakdown Spectroscopy (LIBS)

2020 ◽  
Vol 1 (2) ◽  
pp. 5-8
Author(s):  
Komang Gde Suastika, Heri Suyanto, Gunarjo, Sadiana, Darmaji
Keyword(s):  
Emission Intensity ◽  
Laser Energy ◽  
Emission Spectra ◽  
Atomic Emission ◽  
Laser Induced Breakdown Spectroscopy ◽  
Chemical Formula ◽  
Central Kalimantan ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown

Abstract - Laser-Induced Breakdown Spectroscopy (LIBS) is one method of atomic emission spectroscopy using laser ablation as an energy source. This method is used to characterize the type of amethysts that originally come from Sukamara, Central Kalimantan. The result of amethyst characterization can be used as a reference for claiming the natural wealth of the amethyst. The amethyst samples are directly taken from the amethyst mining field in the District Gem Amethyst and consist of four color variations: white, black, yellow, and purple. These samples were analyzed by LIBS, using laser energy of 120 mJ, delay time detection of 2 μs and accumulation of 3, with and without cleaning. The purpose of this study is to determine emission spectra characteristics, contained elements, and physical characteristics of each amethyst sample. The spectra show that the amethyst samples contain some elements such as Al, Ca, K, Fe, Gd, Ba, Si, Be, H, O, N, Cl and Pu with various emission intensities. The value of emission intensity corresponds to concentration of element in the sample. Hence, the characteristics of the amethysts are based on their concentration value. The element with the highest concentration in all samples is Si, which is related to the chemical formula of SiO2. The element with the lowest concentration in all samples is Ca that is found in black and yellow amethysts. The emission intensity of Fe element can distinguish between white, purple, and yellow amethyst. If Fe emission intensity is very low, it indicates yellow sample. Thus, we may conclude that LIBS is a method that can be used to characterize the amethyst samples.Key words: amethyst, impurity, laser-induced, breakdown spectroscopy, characteristic, gemstones

scholarly journals Erratum to: Theoretical Study of the Electronic Excited States and Fluorescence Spectra of Squaraine in Solution

2014 ◽  
Vol 43 (9-10) ◽  
pp. 1644-1644
Author(s):  
Hitoshi Ozawa ◽  
Kazunori Yashiro ◽  
Takuma Yamamoto ◽  
Satoshi Yabushita
Keyword(s):  
Excited States ◽  
Fluorescence Spectra ◽  
Theoretical Study ◽  
Electronic Excited States

The Synthesis and Electroluminescence Properties of 4-Benzofuranyl-1,8-Naphthalimide Derivatives

2012 ◽  
Vol 557-559 ◽  
pp. 1031-1036 ◽  
Author(s):  
Jian Xin Yang ◽  
Xiang Hui Wang
Keyword(s):  
Absorption Spectra ◽  
Fluorescence Spectra ◽  
Cycloaddition Reaction ◽  
Emission Spectra ◽  
Luminescent Properties ◽  
Quantum Yields ◽  
Absorption And Fluorescence Spectra ◽  
Maximum Brightness ◽  
Maximum Emission ◽  
Mild Conditions

A series of fluorescence compounds, 4-benzofuranyl-1,8-naphthalimides, were prepared through cycloaddition reaction from 4-ethynyl-1,8-naphthalimides and o-iodophenols which catalyzed by a Pd(PPh3)2Cl2 / CuI system under mild conditions. The intermediate material, 4-ethynyl-1,8- naphthalimide, was synthesized from 4-bromo-1,8- naphthalimide and trimethylsilyl- acetylene. The absorption and fluorescence spectra of 4-benzofuranyl-1,8- naphthalimides were studied and the quantum yields were measured. The maximum UV/vis absorption spectra were in the range of 375-400 nm and the maximum emission spectra were in the range of 470-510 nm. The electro- luminescent properties were also mensurated through a doped electroluminescent device which contains 1% 1,8-naphthalimides and 99% CBP (4,4'-N,N'-dicarbazole-biphenyl), It’s shown the maximum brightness reached 3700 cd/ m2 at 22.5V.

scholarly journals Luminescent Hybrid Materials Based on Curcumin Derivatives Embedded in Palygorskite

2018 ◽  
Vol 55 (1) ◽  
pp. 63-67
Author(s):  
Monica Florentina Raduly ◽  
Valentin Raditoiu ◽  
Alina Raditoiu ◽  
Luminita Eugenia Wagner ◽  
Viorica Amariutei ◽  
...  
Keyword(s):  
Hybrid Materials ◽  
Fluorescence Spectra ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Hydroxyl Groups ◽  
Fluorescent Properties ◽  
Fluorescence Emission Spectra ◽  
Curcumin Derivatives ◽  
Absorption Studies ◽  
Inorganic Matrix

The seven curcumin derivatives were deposited on palygorskite in order to obtain hybrid materials. The fluorescence emission spectra of the obtained materials show a decrease in fluorescence intensity relative to the respective dyes, due to the environments around the dyestuff molecules created in the host matrices. Absorption studies show the best adsorption on the inorganic matrix, for the compounds with the hydroxyl groups. Correlating fluorescence spectra of hybrid materials with the results for absorption spectra of the dyes adsorbtion on the surface of the clay lead to the conclusion that a high percentage of the adsorbed dye had the effect of fluorescence quenching. Thus, it was confirmed that the fluorescent properties of hybrid materials depend on the interactions established between the fluorescent dyestuff and the inorganic network.

LASER FLUORESCENCE OF SAND AND CLAY MATERIALS

1977 ◽  
Vol 57 (1) ◽  
pp. 1-8
Author(s):  
A. R. MACK ◽  
E. J. BRACH
Keyword(s):  
Grain Size ◽  
Fluorescence Spectra ◽  
Laser Energy ◽  
Average Power ◽  
Laser Fluorescence ◽  
Regression Estimate ◽  
Airborne Laser ◽  
Wide Range ◽  
Fineness Of Grain ◽  
Clay Materials

Samples of granular materials illuminated with a 20 m Watt (average power) laser energy source at a wavelength of 337.1 nm differed in their fluorescence spectra over a wide range of wavelengths from approximately 380 to 660 nm. The fluorescent yield was usually higher with increased fineness of grain size and with increased concentration of clay (> 10% of under 2-μ grain size). However, sandy soils containing a low content of clay (i.e. < 10%) had a higher yield than the regression estimate. Modifying the fluorosensor for greater resolution at a higher energy level (1 nm bandwidth and 25 m Watt average power) resulted in eight discernible peaks between 384 and 440 nm, at 486 and at 550 nm. Overall fluorescence was markedly increased by removal of Fe coatings from the surface of the grains by a dithionite treatment. Thus, laser-induced fluorescence spectra obtained from various partially vegetated land areas by airborne laser fluorosensing may be influenced by the granular material associated with non-vegetated "open" areas.

scholarly journals Semi-blind sparse affine spectral unmixing of autofluorescence-contaminated micrographs

2019 ◽  
Vol 36 (3) ◽  
pp. 910-917 ◽  
Author(s):  
Blair J Rossetti ◽  
Steven A Wilbert ◽  
Jessica L Mark Welch ◽  
Gary G Borisy ◽  
James G Nagy
Keyword(s):  
Fluorescence Spectra ◽  
Nonnegative Matrix ◽  
Emission Spectra ◽  
Factorization Method ◽  
Reconstruction Error ◽  
Spectral Unmixing ◽  
Great Promise ◽  
Background Fluorescence ◽  
Pixel Location ◽  
Reference Images

Abstract Motivation Spectral unmixing methods attempt to determine the concentrations of different fluorophores present at each pixel location in an image by analyzing a set of measured emission spectra. Unmixing algorithms have shown great promise for applications where samples contain many fluorescent labels; however, existing methods perform poorly when confronted with autofluorescence-contaminated images. Results We propose an unmixing algorithm designed to separate fluorophores with overlapping emission spectra from contamination by autofluorescence and background fluorescence. First, we formally define a generalization of the linear mixing model, called the affine mixture model (AMM), that specifically accounts for background fluorescence. Second, we use the AMM to derive an affine nonnegative matrix factorization method for estimating fluorophore endmember spectra from reference images. Lastly, we propose a semi-blind sparse affine spectral unmixing (SSASU) algorithm that uses knowledge of the estimated endmembers to learn the autofluorescence and background fluorescence spectra on a per-image basis. When unmixing real-world spectral images contaminated by autofluorescence, SSASU greatly improved proportion indeterminacy as compared to existing methods for a given relative reconstruction error. Availability and implementation The source code used for this paper was written in Julia and is available with the test data at https://github.com/brossetti/ssasu.

Surface Modification and Ablation of Insulators Using a Tunable, Picosecond Mid-Infrared Laser

1998 ◽  
Vol 526 ◽  
Author(s):  
R. F. Haglund ◽  
D. R. Ermer ◽  
A. H. Lines ◽  
M. R. Papantonakis ◽  
H. K. Park ◽  
...  
Keyword(s):  
Surface Modification ◽  
Near Infrared ◽  
Energy Content ◽  
Laser Energy ◽  
Vibrational Excitation ◽  
Average Power ◽  
Surface Modifications ◽  
Fused Silica ◽  
Laser Source ◽  
Near Ultraviolet

AbstractUltrashort-pulse lasers with fundamental wavelengths ranging from near-infrared to near-ultraviolet are increasingly being used for laser-induced surface modification of non-metallic solids. The relaxation of the initial electronic excitation into vibrational relaxation modes can produce efficient ablation and other desirable surface modifications with little collateral damage because the laser energy is deposited on a time scale much shorter than thermal diffusion times. Little is known, however, about how ultrashort pulses interact with insulators at wavelengths in the vibrational infrared. This paper describes surface modifications achieved by picosecond laser irradiation in the 2-10 lim range. The laser source was a tunable, free-electron laser (FEL) with I-ps micro-pulses spaced 350 ps apart in a macropulse lasting up to 4 μs, with an average power of up to 3 W. This unusual pulse structure makes possible novel tests of the influences vs fluence and intensity, as well as the effects of resonant vibrational excitation. As model materials systems, we studied calcium carbonate, its isoelectronic cousin sodium nitrate, and fused silica. Particularly intriguing are surface modifications achieved by tuning the laser into vibrational resonances and overtones of the target materials, or by tailoring the energy content of the pulse. The mechanisms underlying these effects, and their implications for materials-modification strategies, are discussed.

Calculs et observations de nouvelles transitions dans le B IV doublement excité

1978 ◽  
Vol 56 (3) ◽  
pp. 358-363 ◽  
Author(s):  
K. X. To ◽  
R. Drouin
Keyword(s):  
Excited States ◽  
Energy Levels ◽  
Emission Spectra ◽  
Doubly Excited States ◽  
Doubly Excited ◽  
Beam Foil

Energy levels of some doubly-excited states are computed using the atomic screening theory. Using these calculations, eight new transitions are identified in the beam-foil emission spectra of helium-like boron. Agreement between predicted wavelengths and those observed is good. Calculated results are included for further applications.

‘Excimer’ fluorescence I. Solution spectra of 1:2-benzanthracene derivatives

1963 ◽  
Vol 274 (1359) ◽  
pp. 552-564 ◽  
Keyword(s):  
Quantum Yield ◽  
Crystal Lattice ◽  
Excited States ◽  
Concentration Dependence ◽  
Fluorescence Spectra ◽  
Excimer Fluorescence ◽  
Relative Quantum Yield ◽  
Relative Quantum ◽  
Different Types ◽  
Excimer Formation

Observations have been made of the concentration dependence of the fluorescence spectra of solutions of 1:2-benzanthracene and fifteen of its hydrocarbon derivatives. All of the compounds, except the 9,10-dim ethyl derivative, exhibit dim er emission at higher concentrations. The lower excited states, 1 L b and 1 L a , satisfy Förster’s conditions for fluorescent dim er formation. The factors determining the relative quantum yield of excimer fluorescence are discussed. The different types of crystal fluorescence spectra shown by the compounds are explained in terms of excimer formation in the crystal lattice.

Sign in / Sign up

Export Citation Format

Share Document