Raman Spectroscopic Studies of Titanium Alkoxides Using UV Excitation

1986 ◽  
Vol 73 ◽  
Author(s):  
Mark J. Payne ◽  
Kris A. Berglund
Keyword(s):  
Spectroscopic Studies ◽  
Excitation Wavelength ◽  
Raman Signal ◽  
Titanium Alkoxides ◽  
Visible Absorption ◽  
Raman Spectroscopic ◽  
Low Concentrations ◽  
Raman Enhancement ◽  
Uv Visible ◽  
Uv Excitation

ABSTRACTThe use of Raman spectroscopy can be greatly hindered by the presence of fluorescing impurities. Even at low concentrations, fluorescence can completely obscure the Raman signal. In the current study, Raman spectra were recorded for various titanium alkoxides (ethoxide, isopropoxide, isobutoxide) as a function of concentration and laser excitation wavelength. It has been shown that fluorescence can be avoided by using uv-excitation (363.8 nm). In addition, titanium alkoxides exhibit a preresonance Raman enhancement as the excitation wavelength appreaches the UV. This result is confirmed by a uv-visible absorption spectrum of the isopropoxide.

scholarly journals Economically reproducible surface-enhanced Raman spectroscopy of different compounds in thin film

2021 ◽  
Vol 45 (1) ◽  
pp. 1-11
Author(s):  
Ahatashamul Islam ◽  
Fariha Tasneem ◽  
Zulfiqar Hasan Khan ◽  
Asif Rakib ◽  
Syed Farid Uddin Farhad ◽  
...  
Keyword(s):  
Au Nanoparticles ◽  
Laser Excitation ◽  
Surface Enhanced Raman Spectroscopy ◽  
Raman Signal ◽  
Visible Absorption ◽  
Sers Substrates ◽  
Raman Enhancement ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Uv Visible

We report herein an economically cheap and functionally stable surfaceenhanced Raman scattering (SERS) protocol of two photoactive pigments Rhodamine 6G (R6G) and Kiton Red (KR), implemented in thin films of silver (Ag) and gold (Au) nanoparticles (AgNPs and AuNPs). Both commercially available and chemically synthesized nanoparticles were used. The suitability of the nanoparticles toward SERS activity was tested through UV-visible absorption spectroscopy and scanning electron microscopy (SEM). The AgNPs and AuNPs based SERS substrates in the form of films were fabricated onto square-sized aluminum(Al) plates by simple drop deposition of colloidal nanoparticles solution onto their polished surfaces. The prepared nanoparticle films were sufficiently dried and coated further with the probe (R6G and KR) molecules by employing the identical deposition technique. The enhanced Raman signals of R6G and KR in such composite film structures were then recorded through a custom-built dispersive Raman spectrometer with He-Ne laser excitation at 632.8 nm. Our AgNPsfilm-based SERS protocol could yield the magnitude of the Raman signal enhancement up to 104 times for both R6G and KR. Moreover, AuNPs-based film was found to be less efficient toward the Raman enhancement of both compounds. Our SERS substrates can be easily fabricated, and SERS spectra are reproducible and stable, allowing one to consistently get a reproducible result even after 6 months. J. Bangladesh Acad. Sci. 45(1); 1-11: June 2021

Controllable Electrochemical Synthesis of Ag Hierarchical Micro/Nanostructures with High SERS-Activity

NANO ◽  
2020 ◽  
Vol 15 (04) ◽  
pp. 2050043
Author(s):  
Huayu Zhou ◽  
Jingjing Wang ◽  
Qiong Yang ◽  
Menglei Chen ◽  
Changsheng Song ◽  
...  
Keyword(s):  
Indium Tin Oxide ◽  
Current System ◽  
Three Dimensional ◽  
Constant Current ◽  
Localized Surface Plasmon ◽  
Excitation Wavelength ◽  
Raman Signal ◽  
Mixed Solution ◽  
Raman Enhancement ◽  
One Step

We report a one-step electrochemical deposition technique to prepare three-dimensional (3D) Ag hierarchical micro/nanostructured film consisting of well-crystallized Ag nanosheets grown on an indium tin oxide (ITO) conductive substrate. The Ag hierarchical micro/nanostructures were fabricated in the mixed solution of AgNO3 and sodium citrate in a constant current system at room temperature. Through reduction of Ag[Formula: see text] electrodeposited on the surface of ITO substrate, nanoparticles were grown to form nanosheets which further combined into 3D sphere-like microstructures. The 3D Ag micro/nanostructures have many sharp edges and nanoscale gaps which can give rise to good Raman-enhanced effect. Due to localized surface plasmon resonance (LSPR) effects, these special Ag micro/nanostructures exhibited good Raman-enhanced performance. Using Rhodamine 6G (R6G) molecules as probe molecule, we studied the influence of excitation wavelength on Raman enhancement. The results showed that the 532[Formula: see text]nm excitation wavelength is the best to obtain the strongest Raman signal and to reduce the influence of other impurity peaks. Using the as-synthesized Ag hierarchical micro/nanostructures, we can detect the 10[Formula: see text][Formula: see text]mol/L R6G aqueous solution, exhibiting great Raman-enhanced effect.

scholarly journals Spectroscopic studies on the interaction of hypocrellin A with myoglobin

2007 ◽  
Vol 21 (4) ◽  
pp. 235-243 ◽  
Author(s):  
J. H. Zhou ◽  
X. H. Wu ◽  
C. Yang ◽  
X. T. Gu ◽  
L. Zhou ◽  
...  
Keyword(s):  
Binding Sites ◽  
Spectroscopic Analysis ◽  
Spectroscopic Studies ◽  
Interaction Process ◽  
Quenching Mechanism ◽  
Visible Absorption ◽  
Paramagnetic Resonance ◽  
Hypocrellin A ◽  
Uv Visible ◽  
Electron Paramagnetic

Experimental results of UV-visible absorption spectroscopy and fluorescence spectroscopy indicate that hypocrellin A, which has been studied in photodynamic therapy, can interact with the surface of myoglobin through hydrophobic forces, and form a complex. Based on the Stern–Volmer equation, the quenching constants of the process can be calculated to be 4.81×1012L mol−1s−1(t=25°C) and 4.54×1012L mol−1s−1(t=42°C) respectively, and the binding constant is 5.53×104M−1(t=25°C), while the binding sites is 0.94 (t=25°C). In addition, Electron paramagnetic resonance and fluorescence spectroscopic analysis suggests that that the quenching mechanism of the interaction process occurs through the electron transfer between hypocrellin A and myoglobin.

Ultraviolet 363.8-nm Raman Spectroscopic System for in Situ Measurements at High Temperatures

1997 ◽  
Vol 51 (8) ◽  
pp. 1224-1228 ◽  
Author(s):  
Masatomo Yashima ◽  
Masato Kakihana ◽  
Ryosuke Shimidzu ◽  
Hirotaka Fujimori ◽  
Masahiro Yoshimura
Keyword(s):  
Raman Scattering ◽  
Raman Spectra ◽  
High Temperatures ◽  
Continuous Wave ◽  
Thermal Emission ◽  
Tetragonal Zirconia ◽  
Raman Signal ◽  
Raman Spectroscopic ◽  
Uv Excitation

A new ultraviolet (UV) Raman spectroscopic system to measure the Raman scattering from materials at high temperatures up to 1500 °C has been designed. This system is based on a CW (continuous-wave) ultraviolet argon-ion laser (363.8 nm), a spatial filter, a single monochromator coupled to a double-grating rejection filter, and a two-dimensional charge-coupled device (CCD) detector. The plasma lines from the laser are almost completely rejected by a Pellin—Broca prism combined with apertures. In situ Raman measurements for a zirconia (ZrO2) specimen at various high temperatures have been performed by using the UV excitation as well as the conventional visible 488.0-nm excitation for comparison. In the case of visible excitation, thermal emission obstructs the observation of the Raman scattering from zirconia even at 900 °C; it becomes rapidly pronounced between 900 and 1100 °C, and finally it is impossible to observe Raman spectra at temperatures higher than 1200 °C. In sharp contrast to the visible excitation, the UV excitation provides good-quality Raman spectra with practically flat backgrounds for the Raman signal of tetragonal zirconia in the spectral region of 20–1100 cm−1 even at 1500 °C, and it enables clear observation of the monoclinic-tetragonal phase transformation of zirconia occurring between 1100 and 1200 °C.

scholarly journals Can ozone be used to calibrate aerosol photoacoustic spectrometers?

2018 ◽  
Vol 11 (12) ◽  
pp. 6419-6427 ◽  
Author(s):  
D. Al Fischer ◽  
Geoffrey D. Smith
Keyword(s):  
Cross Section ◽  
Atmospheric Aerosols ◽  
Excitation Wavelength ◽  
Visible Absorption Spectrum ◽  
Visible Absorption ◽  
Absorption Of Light ◽  
Field Campaigns ◽  
Uv Visible ◽  
532 Nm ◽  
Efficient Transfer

Abstract. Photoacoustic spectroscopy (PAS) has become a popular technique for measuring absorption of light by atmospheric aerosols in both the laboratory and field campaigns. It has low detection limits, measures suspended aerosols, and is insensitive to scattering. But PAS requires rigorous calibration to be applied quantitatively. Often, a PAS instrument is either filled with a gas of known concentration and absorption cross section, such that the absorption in the cell can be calculated from the product of the two, or the absorption is measured independently with a technique such as cavity ring-down spectroscopy. Then, the PAS signal can be regressed upon the known absorption to determine a calibration slope that reflects the sensitivity constant of the cell and microphone. Ozone has been used for calibrating PAS instruments due to its well-known UV–visible absorption spectrum and the ease with which it can be generated. However, it is known to photodissociate up to approximately 1120 nm via the O3 + hν(>1.1eV)→O2(3Σg-) + O(3P) pathway, which is likely to lead to inaccuracies in aerosol measurements. Two recent studies have investigated the use of O3 for PAS calibration but have reached seemingly contradictory conclusions with one finding that it results in a sensitivity that is a factor of 2 low and the other concluding that it is accurate. The present work is meant to add to this discussion by exploring the extent to which O3 photodissociates in the PAS cell and the role that the identity of the bath gas plays in determining the PAS sensitivity. We find a 5 % loss in PAS signal attributable to photodissociation at 532 nm in N2 but no loss in a 5 % mixture of O2 in N2. Furthermore, we discovered a dramatic increase of more than a factor of 2 in the PAS sensitivity as we increased the O2 fraction in the bath gas, which reached an asymptote near 100 % O2 that nearly matched the sensitivity measured with both NO2 and nigrosin particles. We interpret this dependence with a kinetic model that suggests the reason for the observed results is a more efficient transfer of energy from excited O3 to O2 than to N2 by a factor of 22–55 depending on excitation wavelength. Notably, the two prior studies on this topic used different bath gas compositions, and although the results presented here do not fully resolve the differences in their results, they may at least partially explain them.

Raman Spectroscopic Studies of Amsacrine

1992 ◽  
Vol 46 (10) ◽  
pp. 1540-1544 ◽  
Author(s):  
Catherine A. Butler ◽  
Ralph P. Cooney ◽  
William A. Denny
Keyword(s):  
Crystal Structure ◽  
Raman Spectroscopy ◽  
Crystal Structure Data ◽  
Visible Spectrum ◽  
Spectroscopic Studies ◽  
Resonance Raman Spectrum ◽  
Raman Spectroscopic ◽  
Ft Raman Spectroscopy ◽  
Uv Visible ◽  
Ft Raman

Amsacrine (4′-(9-acridinylamino)methanesulfon- m-anisidide) in both solid and aqueous forms was characterized with the use of resonance and nonresonance Raman spectroscopy (including FT-Raman spectroscopy). Evidence that the acridine nucleus is the dominant chromophoric unit contributing to the resonance Raman spectrum is based upon the apparent similarities of the spectra of aqueous amsacrine (in the unpro-tonated form) and acridine (in ethanol). The probable non-coplanarity of the acridine and phenyl units in the amsacrine molecule (based on previously reported crystal structure data) is consistent with the suggestion that the acridine nucleus may constitute an independent chromophoric unit. Further evidence is derived from analysis of the UV-visible spectrum, which indicates that excitation at 457.9 nm falls within an electronic transition of the acridine nucleus of amsacrine. The excitation profiles of aqueous amsacrine are presented, and four types of profiles have been identified.

Spectroscopic Studies of the Interaction of 1,4-Diphenyl-1,3-Butadiene with α-, β-, and γ-Cyclodextrins

1997 ◽  
Vol 51 (2) ◽  
pp. 153-159 ◽  
Author(s):  
Arsenio Muñoz de la Peña ◽  
Rezik A. Agbaria ◽  
Montserrat Sánchez Peña ◽  
Isiah M. Warner
Keyword(s):  
Fluorescence Emission ◽  
Spectroscopic Studies ◽  
Visible Absorption ◽  
Spectral Shifts ◽  
Equilibrium Reaction ◽  
High Anisotropy ◽  
Spectroscopic Characteristics ◽  
Uv Visible ◽  
High Absorption ◽  
Absorption Measurements

Steady-state fluorescence, anisotropy, and UV-visible absorption measurements have been used to investigate the structure and spectroscopic characteristics of the complexes formed by trans, trans-1,4-diphenyl-1,3-butadiene (DPB) with α-, β-, and γ-cyclodextrins (CDs). The behavior of α-CD with DPB is very different from that of DPB with respect to β-CD or γ-CD. In the presence of α-CD, clear solutions with high absorption and fluorescence emission, relatively high anisotropy, a rapid equilibrium reaction, and Benesi–Hildebrand plots lead us to conclude that normal 2:1 inclusion compounds are formed. In the presence of γ-CD, turbid solutions, with absorption and fluorescence emission intensities lower than those in α-CD, higher values of anisotropy, slow equilibrium reaction, and spectral shifts to the red in the absorption, excitation, and emission wavelengths are evidence of the formation of extended linear aggregates. In the presence of β-CD, both mechanisms of inclusion appear to be present.

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