scholarly journals Defect Related Emission in Calcium Hydroxide: The Controversial Band at 780 cm−1

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 266 ◽  
Author(s):  
Francesca Assunta Pisu ◽  
Daniele Chiriu ◽  
Pier Carlo Ricci ◽  
Carlo Maria Carbonaro
Keyword(s):  
Cultural Heritage ◽  
Calcium Hydroxide ◽  
Raman Spectra ◽  
Near Infrared ◽  
Specific Treatment ◽  
Emission Spectra ◽  
Infrared Region ◽  
Carbonation Process ◽  
Composite Band ◽  
Post Synthesis

Calcium hydroxide, a crystal involved in the cycle of calcination and carbonation of calcium oxide, finds several applications from cultural heritage to the dentistry branch or to the construction industry. When excited at 1064 nm, Raman spectra of calcium hydroxide show a broad composite band peaked at about 780 cm−1, corresponding to 1170 nm. Since it is not observed with visible excitation, the origin of this band is debated, being assigned to some pre-existent luminescent impurities or some structural defect of the lime formed after the synthesis of the material. To shed light on the formation of this band, we synthetised the lime paste starting from pure calcite powders. The obtained fresh Ca(OH)2 samples did not show any band in the investigated range, irrespective of the laser excitation applied. A detailed analysis of the excitation and emission spectra in the near infrared region did not show the 1170 nm band, supporting the hypothesis of a post-synthesis origin. Thus, we carried out thermal treatments at different temperatures (90–500 °C) and under different environments (in air or under nitrogen flux) on synthesised fresh Ca(OH)2 powders. We also investigated the time evolution of the samples, monitoring the Raman spectra over 90 days after a specific treatment. The collected data support the hypothesis of a defect-related luminescence centre, whose formation depends on the temperature and environment of the treatment, which appears as a preferential site for the carbonation process of the calcium hydroxide. These results can be useful in the field of Cultural Heritage for dating purposes, and to determine the conservation state of Ca(OH)2 containing relics to prevent the possible activation of degradation processes.

scholarly journals Fresco Paintings: Development of an Aging Model from 1064 nm Excited Raman Spectra

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 257
Author(s):  
Francesca Assunta Pisu ◽  
Carlo Maria Carbonaro ◽  
Riccardo Corpino ◽  
Pier Carlo Ricci ◽  
Daniele Chiriu
Keyword(s):  
Raman Spectroscopy ◽  
Kinetic Model ◽  
Cultural Heritage ◽  
Calcium Hydroxide ◽  
Raman Spectra ◽  
Diagnostic Tool ◽  
Wall Paintings ◽  
Aging Model ◽  
Carbonation Process ◽  
Preliminary Model

In this study, we proposed a preliminary kinetic model applied to the carbonation process of fresh lime with the intention to realize a diagnostic tool for aged fresco paintings. The model can be useful, in particular, in the fields of conservation and restoration of ancient lime wall paintings. The dating procedure was achieved through the analysis of 1064 nm excited Raman spectra collected on artificially aged lime samples in addition to ancient samples taken from literature and covering a period of two thousand years. The kinetic model was developed monitoring the concentration of emitting defective centers related to the intensity of 780 cm−1 calcium hydroxide band as a function of the time and depth. This preliminary model shows how Raman spectroscopy, especially NIR micro-Raman, is advantageous for diagnostics and conservation in the cultural heritage field.

Luminescent Properties and Thermometry of CaWO4:Nd3+ in Near Infrared Region

2017 ◽  
Vol 893 ◽  
pp. 156-160
Author(s):  
Rong Xue Wang ◽  
Xiao Bing Luo
Keyword(s):  
Near Infrared ◽  
Emission Spectra ◽  
Luminescent Properties ◽  
Infrared Region ◽  
Excitation Spectra ◽  
Efficient Energy Transfer ◽  
Fluorescent Intensity ◽  
Sensor Device ◽  
The Matrix ◽  
Increasing Temperature

CaWO4: xNd3+ (x = 0.005, 0.008, 0.01, 0.015, 0.02, 0.025 0.03) powders have been synthesized by high-temperature solid state reaction. The results of the XRD indicate that Nd3+ ions have entered into the crystal lattice in all compounds successfully. The reflectance spectra show that the matrix has strong absorption. The emission spectra, excitation spectra and different lifetimes between CaWO4 and CaWO4: 0.5% Nd3+ indicate that efficient energy transfer occurs from WO42- cluster to Nd3+ ions. On the basis of the above work, the dependence of fluorescent spectra on temperature was studied. It turned out that, not only the excitation spectra appeared red shift with increasing temperature, but also the dependence of the near infrared fluorescent intensity on temperature is fitting with a linear function. It might be served as a promising phosphor for temperature sensor device.

scholarly journals STRUCTURAL AND OPTICAL PROPERTIES IN NEAR INFRARED OF CdTeSe COLOIDAL QUANTUM DOTS FOR POTENTIAL APPLICATION IN SOLAR CELLS

2017 ◽  
Vol 55 (4) ◽  
pp. 515
Author(s):  
Pham Nam Thang ◽  
Le Xuan Hung ◽  
Nguyen Thi Minh Chau ◽  
Vu Thi Hong Hanh ◽  
Nguyen Ngoc Hai ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Solar Cells ◽  
Raman Spectra ◽  
Near Infrared ◽  
Emission Spectra ◽  
Structural Vibration ◽  
Absorption Region ◽  
Composition Ratio ◽  
Different Temperatures

Abstract: This report presents the results on the optical properties of CdTeSe ternary alloyed quantum dots (QDs) fabricated by colloidal chemical method. We have used the micro-Raman spectra as a tool to determine the formation of CdTeSe alloy phase, the composition ratio of Te:Se when fabricated at different temperatures from 180 oC to 280 oC. The intensity ratio of two vibration lines at 159 cm-1 and 188 cm-1 allows the determination of Te:Se composition ratio available in QD samples. The Raman spectra of CdTexSe1-x when x changes between 0, 0.2, 0.4, 0.5, 0.6, 0.8 and 1, fabricated at 260 oC, shows clearly the change in intensity of the optical vibration lines. The  absorption and emission spectra of CdTeSe QDs show that the absorption edge of these QDs shifts up to 880 nm and up to ~ 860 nm for the emission. Detailed studies on size, structural, vibration and optical characteristics of ternary alloyed QDs are also discussed. The absorption region of fabricated CdTeSe QDs are completely suitable for usage in solar cells.

The formation and detection of some low-lying excited electronic states of BrCl and other halogens

1967 ◽  
Vol 298 (1455) ◽  
pp. 424-452 ◽  
Keyword(s):  
Ground State ◽  
Near Infrared ◽  
Transfer Reaction ◽  
Potential Energy Curve ◽  
Emission Spectra ◽  
Infrared Region ◽  
Band Head ◽  
Energy Curve ◽  
Chlorine Atoms ◽  
Formula Type

Forty-nine bands arising from have been detected in the emission spectrum of from two sources: (i) the reaction of Br or Br 2 with ClO 2 , in which is populated in the transfer reaction, 3 and (ii) the radiative combination of bromine and chlorine atoms, 5 The populations of the higher levels of formed in reaction (3) are less than in reaction (5). In reaction (3), is evidently formed via a triangular transition state similar to that postulated previously; the rate constant, k 3 , was found to be The combination of ground state iodine , and chlorine atoms was also found to be chemiluminescent in the red and near infrared region, and fifty-seven bands of the system , with , have been recorded. The radiative combination of ground-state chlorine atoms has been reinvestigated, and transitions of from v ' ≼ 14 have been detected. Combining band head analyses of these emission spectra with previous data, the following constants (in cm -1 ) are reported: The reasons for the predominant radiation, during atom combination processes, from type states for Cl 2 and BrCl, and from the 3 II 1 state for ICl, are discussed in relation to Brown & Gibson’s (1932) finding of a maximum in the potential energy curve of leading to and as dissociation products.

Characterization of Near-Infrared Nonmetal Atomic Emission from an Atmospheric Helium Microwave-Induced Plasma Using a Fourier Transform Spectrophotometer

1986 ◽  
Vol 40 (6) ◽  
pp. 759-766 ◽  
Author(s):  
Joseph Hubert ◽  
Huu Van Tra ◽  
Khanh Chi Tran ◽  
Frederick L. Baudais
Keyword(s):  
Fourier Transform ◽  
Near Infrared ◽  
Microwave Plasma ◽  
Emission Spectra ◽  
Plasma Source ◽  
Atomic Emission ◽  
Infrared Region ◽  
Emission Lines ◽  
Helium Plasma ◽  
Microwave Induced Plasma

A new approach for using Fourier transform spectroscopy (FTS) for the detection of atomic emission from an atmospheric helium plasma has been developed and the results obtained are described. Among the different types of plasma source available, the atmospheric pressure microwave helium plasma appears to be an efficient excitation source for the determination of nonmetal species. The more complete microwave plasma emission spectra of Cl, Br, I, S, O, P, C, N, and He in the near-infrared region were obtained and their corrected relative emission intensities are reported. This makes qualitative identification simple, and aids in the quantitative analysis of atomic species. The accuracy of the emission wavelengths obtained with the Fourier transform spectrophotometer was excellent and the resolution provided by the FTS allowed certain adjacent emission lines to be resolved. These atomic emission lines were found to be adequate for analytical applications.

A Visible Near-Infrared Hadamard Transform Spectrometer Based on a Liquid Crystal Spatial Light Modulator Array: A New Approach in Spectrometry

1987 ◽  
Vol 41 (5) ◽  
pp. 727-734 ◽  
Author(s):  
D. C. Tilotta ◽  
R. M. Hammaker ◽  
W. G. Fateley
Keyword(s):  
Liquid Crystal ◽  
Spatial Light Modulator ◽  
Near Infrared ◽  
Liquid Crystal Display ◽  
Emission Spectra ◽  
Infrared Region ◽  
Hadamard Transform ◽  
Light Modulator ◽  
New Approach ◽  
Single Detector

A stationary Hadamard encodement mask has been designed from a liquid crystal display. This mask, when properly installed and positioned in a dispersive instrument, allows the selected Hadamard encoded spectral elements to be focused on a single detector. Discussion of the advantages derived by this technique is presented. Several emission spectra in the visible and near-infrared region demonstrate the usefulness of the Hadamard transform technique. This novel spectrometer can provide a no-moving-parts spectroscopy for future spectral applications.

scholarly journals Формирование аморфных нанокластеров и нанокристаллов германия в пленках GeSi-=SUB=-x-=/SUB=-O-=SUB=-y-=/SUB=- на кварцевой подложке с использованием печных и импульсных лазерных отжигов

2020 ◽  
Vol 54 (3) ◽  
pp. 251
Author(s):  
Zhang Fan ◽  
С.А. Кочубей ◽  
M. Stoffel ◽  
H. Rinnert ◽  
M. Vergnat ◽  
...  
Keyword(s):  
Raman Spectra ◽  
Absorption Edge ◽  
Near Infrared ◽  
Laser Annealing ◽  
High Vacuum ◽  
Infrared Region ◽  
Fused Silica ◽  
Silica Substrate ◽  
Germanium Nanocrystals ◽  
Germanium Clusters

Abstract Nonstoichiometric GeO_0.5[SiO_2]_0.5 and GeO_0.5[SiO]_0.5 germanosilicate glassy films are produced by the high-vacuum coevaporation of GeO_2 and either SiO or SiO_2 powders with deposition onto a cold fused silica substrate. Then the films are subjected to furnace or laser annealing (a XeCl laser, λ = 308 nm, pulse duration of 15 ns). The properties of the samples are studied by transmittance and reflectance spectroscopy, Raman spectroscopy, and photoluminescence spectroscopy. As shown by analysis of the Raman spectra, the GeO[SiO] film deposited at a substrate temperature of 100°C contains amorphous Ge clusters, whereas no signal from Ge–Ge bond vibrations is observed in the Raman spectra of the GeO[SiO_2] film deposited at the same temperature. The optical absorption edge of the as-deposited GeO[SiO_2] film corresponds to ~400 nm; at the same time, in the GeO[SiO] film, absorption is observed right up to the near-infrared region, which is apparently due to absorption in Ge clusters. Annealing induces a shift of the absorption edge to longer wavelengths. After annealing of the GeO[SiO_2] film at 450°C, amorphous germanium clusters are detected in the film, and after annealing at 550°C as well as after pulsed laser annealing, germanium nanocrystals are detected. The crystallization of amorphous Ge nanoclusters in the GeO[SiO] film requires annealing at a temperature of 680°C. In this case, the size of Ge nanoclusters in this film are smaller than that in the GeO[SiO_2] film. It is not possible to crystallize Ge clusters in the GeO[SiO] film. It seems obvious that the smaller the semiconductor nanoclusters in an insulating matrix, the more difficult it is to crystallize them. In the low-temperature photoluminescence spectra of the annealed films, signals caused by either defects or Ge clusters are detected.

Spectroscopy with a Light Optical Microscope

2012 ◽  
Vol 21 (1) ◽  
pp. 22-26
Author(s):  
Paul Martin
Keyword(s):  
Near Infrared ◽  
Emission Spectra ◽  
Infrared Region ◽  
Optical Microscope ◽  
Infrared Range ◽  
Molecular Spectra ◽  
Light Optical Microscope ◽  
Deep Ultraviolet ◽  
Uv Visible ◽  
Near Infrared Range

The microspectrophotometer can be described as a type of hyphenated instrument: it is a hybrid that combines the magnifying power of a light microscope with a UV-visible-NIR (ultraviolet–visible–near infrared) range spectrophotometer. These instruments are used to measure the molecular spectra from microscopic samples, from the deep ultraviolet to the near infrared region. Microspectrophotometers can be configured in many different ways and used to measure absorbance, reflectance, and even emission spectra, such as fluorescence, of sub-micron-sized sample areas. With the addition of specialized algorithms, the microspectrophotometer can also be used to measure the thickness of thin films or to act as a colorimeter for microscopic samples.

Rapid Near-Infrared Raman Spectroscopy of Human Tissue with a Spectrograph and CCD Detector

1992 ◽  
Vol 46 (2) ◽  
pp. 187-190 ◽  
Author(s):  
Joseph J. Baraga ◽  
Michael S. Feld ◽  
Richard P. Rava
Keyword(s):  
Raman Spectra ◽  
Near Infrared ◽  
Broad Band ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Human Artery ◽  
Broad Band Emission ◽  
Band Emission ◽  
Ccd Detector

We demonstrate the use of a single-stage spectrograph and charge-coupled-device (CCD) detector to collect near-infrared (NIR) Raman spectra from intact human arterial tissue. With 810-nm excitation, the fluorescence emission from human artery is sufficiently weak to allow observation of Raman bands more rapidly with the spectrograph/CCD system than with 1064-nm excited FT-Raman systems. We also present a method for removing the broad-band emission from the spectra by computing the difference of two emission spectra collected at slightly different excitation frequencies. Our results indicate that NIR Raman spectra can be collected in under one second with the spectrograph/CCD system and an optical fiber probe, opening the possibility of in vivo clinical applications.

Sign in / Sign up

Export Citation Format

Share Document