scholarly journals Observation of microsecond luminescence while studying two DNA-stabilized silver nanoclusters emitting in the 800-900 nm range.

2021 ◽  
Author(s):  
Vanessa Rück ◽  
Cecilia Cerretani ◽  
Vlad Andrei Neacsu ◽  
Mikkel Liisberg ◽  
Tom Vosch
Keyword(s):  
Visible Region ◽  
Silver Nanoclusters ◽  
Multiple Absorption ◽  
Absorption Features ◽  
Nm Range

We investigated two DNA-stabilized silver nanoclusters (DNA-AgNCs) that show multiple absorption features in the visible region, and emit around 811 nm (DNA811-AgNC) and 841 nm (DNA841-AgNC). Both DNA-AgNCs have large...

scholarly journals Ultrafast Electron/Energy Transfer and Intersystem Crossing Mechanisms in BODIPY-Porphyrin Compounds

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 312
Author(s):  
Yusuf Tutel ◽  
Gökhan Sevinç ◽  
Betül Küçüköz ◽  
Elif Akhuseyin Yildiz ◽  
Ahmet Karatay ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Fluorescence Spectra ◽  
Visible Region ◽  
Energy Transfer Mechanism ◽  
Free Base ◽  
Pump Probe ◽  
Harvesting Efficiency ◽  
Probe Spectroscopy ◽  
Absorption Features ◽  
Transfer Mechanisms

Meso-substituted borondipyrromethene (BODIPY)-porphyrin compounds that include free base porphyrin with two different numbers of BODIPY groups (BDP-TTP and 3BDP-TTP) were designed and synthesized to analyze intramolecular energy transfer mechanisms of meso-substituted BODIPY-porphyrin dyads and the effect of the different numbers of BODIPY groups connected to free-base porphyrin on the energy transfer mechanism. Absorption spectra of BODIPY-porphyrin conjugates showed wide absorption features in the visible region, and that is highly valuable to increase light-harvesting efficiency. Fluorescence spectra of the studied compounds proved that BODIPY emission intensity decreased upon the photoexcitation of the BODIPY core, due to the energy transfer from BODIPY unit to porphyrin. In addition, ultrafast pump-probe spectroscopy measurements indicated that the energy transfer of the 3BDP-TTP compound (about 3 ps) is faster than the BDP-TTP compound (about 22 ps). Since the BODIPY core directly binds to the porphyrin unit, rapid energy transfer was seen for both compounds. Thus, the energy transfer rate increased with an increasing number of BODIPY moiety connected to free-base porphyrin.

STANDOFF SENSING AND IMAGING OF EXPLOSIVE RELATED CHEMICAL AND BIO-CHEMICAL MATERIALS USING THz-TDS

2007 ◽  
Vol 17 (02) ◽  
pp. 239-249 ◽  
Author(s):  
Hua Zhong ◽  
Albert Redo-Sanchez ◽  
Xi-Cheng Zhang
Keyword(s):  
Remote Sensing ◽  
Glutamic Acid ◽  
Time Domain ◽  
Large Scale ◽  
Imaging System ◽  
Terahertz Time Domain Spectroscopy ◽  
Multiple Absorption ◽  
Thz Absorption ◽  
Absorption Features ◽  
Chemical Materials

We report the sensing and imaging of explosive related chemical and bio-chemical materials by using terahertz time domain spectroscopy (THz-TDS) at standoff distance. The 0.82 THz absorption peak of RDX is observed at a distance up to 30 m away from the emitter and receiver. Multiple absorption features of RDX, 2,4-DNT and Glutamic Acid are identified by using a large scale 2-D imaging system. These results support the feasibility of using THz-TDS technique in remote sensing and detection of chemical materials.

Interpretations of multiple absorption features in a gamma-ray burst spectrum

1988 ◽  
Vol 335 ◽  
pp. L71 ◽  
Author(s):  
E. E. Fenimore ◽  
J. P. Conner ◽  
R. I. Epstein ◽  
R. W. Klebesadel ◽  
J. G. Laros ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Burst ◽  
Multiple Absorption ◽  
Burst Spectrum ◽  
Absorption Features

scholarly journals Debris discs with multiple absorption features in metallic lines: circumstellar or interstellar origin?

2018 ◽  
Vol 480 (1) ◽  
pp. 488-520 ◽  
Author(s):  
D Iglesias ◽  
A Bayo ◽  
J Olofsson ◽  
Z Wahhaj ◽  
C Eiroa ◽  
...  
Keyword(s):  
Multiple Absorption ◽  
Absorption Features

scholarly journals Aerosol single scattering albedo retrieved from ground-based measurements in the UV and visible region

2011 ◽  
Vol 4 (1) ◽  
pp. 1-7 ◽  
Author(s):  
V. Buchard ◽  
C. Brogniez ◽  
F. Auriol ◽  
B. Bonnel
Keyword(s):  
Optical Thickness ◽  
Visible Region ◽  
Single Scattering ◽  
Single Scattering Albedo ◽  
Mean Square ◽  
Spectral Measurements ◽  
Aerosol Absorption ◽  
Uv Visible ◽  
Nm Range ◽  
Uv Range

Abstract. Estimates of Aerosol Single Scattering Albedo (SSA) from ground-based spectral measurements in the UV-visible are conducted at Villeneuve d'Ascq (VdA) in France. In order to estimate this parameter, measurements of global and diffuse UV-visible solar irradiances performed under cloud-free conditions since 2003 with a spectroradiometer operated by the Laboratoire d'Optique Atmosphérique (LOA) are used. The technique consists in comparing the measured irradiance values to modelled irradiances computed for various SSA. The retrieval is restricted to the 330–450 nm range to avoid ozone influence. For validation purpose, the retrieved values of SSA at 440 nm are compared to the ones obtained from sunphotometer measurements of the AERONET/PHOTONS network available on the LOA site. The results are rather satisfying: for the period 2003–2006 the Root Mean Square (RMS) of the differences is about 0.05, this value is within the uncertainty domain of retrieval of both products. Distinction between days characterized by different aerosol content, by means of the aerosol optical thickness (AOT) retrieved from ground-based measurements at the same wavelength, shows that the comparisons between both products are better when AOT are higher. Indeed in case AOT are greater than 0.2, the RMS is 0.031 compared to 0.060 for days with an AOT lower than 0.2. The SSA estimated at 340 and 380 nm from ground-based spectra are also studied, though no validation can be carried out with sunphotometer data (440 nm is the shortest wavelength at which the SSA is provided by the network). The good comparisons observed at 440 nm can let assume that the SSA retrieved from spectroradiometer measurements at the two other wavelengths are also obtained with a good confidence level. Thus these values in the UV range can be used to complete aerosol data provided by AERONET/PHOTONS at VdA. Moreover they can be used for a best knowledge of the aerosol absorption that is necessary to quantify the error on surface UV irradiances estimated from satellites.

scholarly journals Organic compounds as carriers of the diffuse interstellar bands

2008 ◽  
Vol 4 (S251) ◽  
pp. 49-56 ◽  
Author(s):  
Peter J. Sarre
Keyword(s):  
Organic Compounds ◽  
Organic Material ◽  
Visible Region ◽  
Huge Amount ◽  
Diffuse Interstellar Bands ◽  
Polycyclic Aromatic Hydro ◽  
Hydro Carbon ◽  
Polycyclic Aromatic ◽  
Absorption Features

AbstractThe diffuse interstellar bands appear as absorption features in spectra of reddened stars and lie mostly in the visible region of the spectrum. The first examples were recorded photographically nearly one hundred years ago and despite a huge amount of observational, theoretical and laboratory effort the spectra remain unassigned. Most researchers believe that organic material is responsible for the absorptions, the most popular form being polycyclic aromatic (hydro)carbon (PAH) structures. This article reviews briefly the main characteristics of the spectrum, describes some current research and outlines some lines of inquiry.

Enhanced Electroluminescence of Urethane Containing Processable Polythiophene Derivative by Addition of Dye Molecules

2000 ◽  
Vol 660 ◽  
Author(s):  
Amarjeet Kaur ◽  
Mario J. Cazeca ◽  
Kethinni G. Chittibabu ◽  
Jayant Kumar ◽  
Sukant K. Tripathy
Keyword(s):  
Fluorescent Dyes ◽  
Visible Region ◽  
Dye Molecules ◽  
Flat Panel Display ◽  
Large Area ◽  
Good Efficiency ◽  
Display Devices ◽  
Yellow Color ◽  
Organic Electroluminescent ◽  
Important Approach

ABSTRACTOrganic electroluminescent (EL) diodes based on fluorescent dyes and conducting polymers have attracted the interest of researchers, mainly because of their emission in the visible region and for application to large area portable flat panel display devices, driven at low voltages. Therefore, for the development of higher efficiency polymer EL diodes, the optimal combination of the merits of organic fluorescent dye molecules with that of conjugated polymer is an important approach. We report electroluminescence studies of polymer light emitting diodes (p-LEDs) fabricated with poly[2-(3-thienyl)ethanol n-butoxy carbonylmethyl urethane] (PURET) and its composite with 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H pyran (DCM) dye. These materials have been chosen in view of the fact that PURET exhibits a small overlap between emission and absorption spectra whereas DCM has a good efficiency of trapping both electrons as well as holes. Polyaniline has been utilized as hole injecting layer whereas tris-8-hydroxyquinoline-aluminum as electron injecting layer. Enhanced electroluminescence with bright yellow color has been observed in p-LEDs by the addition of dye.

Effect of trytophan as dopant on potassium acid phthalate single crystals

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Single Crystals ◽  
Room Temperature ◽  
Visible Region ◽  
X Ray Diffraction ◽  
X Ray ◽  
Slow Evaporation Technique ◽  
Absorption Studies ◽  
Evaporation Technique ◽  
Potassium Acid Phthalate ◽  
Acid Phthalate

Optically transparent single crystals of potassium acid phthalate (KAP, 0.5 g) 0.05 g and 0.1 g (1 and 2 mol %) trytophan were grown in aqueous solution by slow evaporation technique at room temperature. Single crystal X- ray diffraction analysis confirmed the changes in the lattice parameters of the doped crystals. The presence of functional groups in the crystal lattice has been determined qualitatively by FTIR analysis. Optical absorption studies revealed that the doped crystals possess very low absorption in the entire visible region. The dielectric constant has been studied as a function of frequency for the doped crystals. The thermal stability was evaluated by TG-DSC analysis.

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