scholarly journals Wavelength-Dependent Nonlinear Absorption in Palladium Nanoparticles

2021 ◽  
Vol 11 (4) ◽  
pp. 1640
Author(s):  
Chunyu Chen ◽  
Jun Wang ◽  
Yachen Gao
Keyword(s):  
Surface Plasmon Resonance ◽  
Excitation Energy ◽  
Systematic Study ◽  
Nonlinear Absorption ◽  
Palladium Nanoparticles ◽  
Excitation Wavelength ◽  
Saturated Absorption ◽  
Multi Wavelength ◽  
Resonant Region ◽  
Absorption Characteristics

This paper aims to study the nonlinear absorption characteristics of palladium nanoparticles (PdNPs) at off-resonant wavelengths. For this purpose, multi-wavelength (500–650 nm) nanosecond Z-scan technique was used. The experimental results indicate that saturated absorption (SA) and the transition from SA to reverse saturated absorption (RSA) can occur, and depends on the excitation wavelength and energy. When the excitation wavelength is constant, with the increase of excitation energy, PdNPs change from SA to RSA. When the excitation energy is constant, with the excitation wavelength approaching surface plasmon resonance (SPR), PdNPs change from SA to RSA. This phenomenon of SA and RSA under multi-wavelength excitation in the off-resonant region provides a supplement for the systematic study of the nonlinear absorption of PdNPs.

scholarly journals Palladium nanoparticles anchored to anatase TiO2 for enhanced surface plasmon resonance-stimulated, visible-light-driven photocatalytic activity

2015 ◽  
Vol 6 ◽  
pp. 428-437 ◽  
Author(s):  
Kah Hon Leong ◽  
Hong Ye Chu ◽  
Shaliza Ibrahim ◽  
Pichiah Saravanan
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Surface Plasmon Resonance ◽  
Visible Light ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Palladium Nanoparticles ◽  
Noble Metals ◽  
Visible Region ◽  
Bet Surface Area

Freely assembled palladium nanoparticles (Pd NPs) on titania (TiO2) nano photocatalysts were successfully synthesized through a photodeposition method using natural sunlight. This synthesized heterogeneous photocatalyst (Pd/TiO2) was characterized through field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), BET surface area, UV–vis diffuse reflectance spectra (UV-DRS), Raman and photoluminescence (PL) analyses. The simple and smart synthesis anchored well the deposition with controlled Pd NPs size ranging between 17 and 29 nm onto the surface of TiO2. Thus, it gives the characteristic for Pd NPs to absorb light in the visible region obtained through localized surface plasmon resonance (LSPRs). Apparently, the photocatalytic activity of the prepared photocatalysts was evaluated by degrading the endocrine disrupting compound (EDC) amoxicillin (AMX) excited under an artificial visible light source. In the preliminary run, almost complete degradation (97.5%) was achieved in 5 h with 0.5 wt % Pd loading and the degradation followed pseudo-first-order kinetics. The reusability trend proved the photostability of the prepared photocatalysts. Hence, the study provides a new insight about the modification of TiO2 with noble metals in order to enhance the absorption in the visible-light region for superior photocatalytic performance.

Nonlinear absorption characteristics of piezopolar semiconductor plasmas

2020 ◽  
Author(s):  
Ratna Agrawal ◽  
Ravi Vanshpal ◽  
Swati Dubey ◽  
S. Ghosh
Keyword(s):  
Nonlinear Absorption ◽  
Semiconductor Plasmas ◽  
Absorption Characteristics

Controlling the nonlinear absorption characteristics of TiO2/carbon nanocomposites on films

2018 ◽  
Vol 108 ◽  
pp. 510-514 ◽  
Author(s):  
Ahmet Karatay ◽  
Yusuf Osman Donar ◽  
Ali Sınağ ◽  
Ayhan Elmali
Keyword(s):  
Nonlinear Absorption ◽  
Carbon Nanocomposites ◽  
Absorption Characteristics

Excitation Energy-Dependent Transient Spectral Relaxation of Coumarin 153

1998 ◽  
Vol 52 (1) ◽  
pp. 82-90 ◽  
Author(s):  
W. C. Flory ◽  
G. J. Blanchard
Keyword(s):  
Excitation Energy ◽  
Spectral Response ◽  
Excitation Wavelength ◽  
Spectral Evolution ◽  
Relative Contribution ◽  
Coumarin 153 ◽  
Central Result ◽  
Spectral Relaxation ◽  
Evolution Behavior ◽  
Energy Dependent

We report on the excitation energy-dependent transient spectral response of the polar dye molecule coumarin 153 (C153) in selected solvents. We find that the blue edge of the spontaneous emission spectrum of C153 contains several spectral features and that the relative contribution of these features to the overall response varies with the identity of the solvent and the excitation wavelength. The central result of these data is that the transient spectral response of C153 depends sensitively on the excitation wavelength and that the spectral evolution behavior of this molecule is therefore not related in a simple manner to solvent reorganization dynamics.

Excitation Wavelength Dependent Raman Scattering in Low and Highly Degenerate InN Films

2004 ◽  
Vol 831 ◽  
Author(s):  
V.M. Naik ◽  
H. Dai ◽  
R. Naik ◽  
D.B. Haddad ◽  
J.S. Thakur ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Raman Scattering ◽  
Excitation Energy ◽  
Raman Spectra ◽  
Molecular Beam ◽  
Optical Bandgap ◽  
Structural Defects ◽  
Excitation Wavelength ◽  
Phonon Modes ◽  
Energy Mode

ABSTRACTThe Raman spectra of low and highly degenerate InN films grown by conventional Molecular Beam Epitaxy (MBE) and Plasma Source Molecular Beam Epitaxy (PSMBE) have been studied using visible (514.5 nm) and near infrared (785 nm) excitation wavelengths. The MBE grown InN films have a low electron carrier concentration, ne < 2.0 × 1019 cm−3, exhibiting an optical bandgap absorption edge of 0.6 to 0.7 eV. On the other hand PSMBE grown InN samples are highly degenerate with ne > 3 × 1020 cm−3 with an observed optical bandgap ranging from 1.5 to 1.9 eV. Raman spectra of low degenerate InN films show sharp E2 and A1(LO) modes whereas spectra of highly degenerate InN films show rather broad features indicating the presence of a large number of structural defects. In the latter samples a resonance enhanced Raman scattering is observed especially with 785 nm excitation energy, where the excitation energy matches the optical energy bandgap. Another interesting observation is that the expected coupled plasmon LO-phonon modes are not detected in these films, rather a phonon mode is observed at the location of the unscreened A1(LO) mode. The observation of unscreened LO-phonon, and the absence of coupled plasmon LO-phonon modes have been attributed to Landau damping of the higher energy mode and coupling of the lower energy mode with the electron-hole pair excitations leading to the emergence of a mode very close to the A1(LO) mode.

scholarly journals Structure-Photochemical Function Relationships in Nitrogen-Containing Heterocyclic Aromatic Photobases Derived from Quinoline

2019 ◽  
Author(s):  
Sophya Alamudun ◽  
Kyle Tanovitz ◽  
April Fajardo ◽  
Kaitlind Johnson ◽  
Andy Pham ◽  
...  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Excitation Energy ◽  
Systematic Study ◽  
Experimental Studies ◽  
Substituent Effects ◽  
Vertical Excitation ◽  
Vertical Excitation Energy ◽  
Heterocyclic Aromatics ◽  
A Charge

<p>Photobases are compounds which become strong bases after electronic excitaton into a charge-transfer excited state. Recent experimental studies have highlighted the photobasicity of the 5-R quinoline compounds, demonstrating a strong substituent dependence to the pK<sub>a</sub><sup>*</sup>. Here we describe our systematic study of how the photobasicity of four families of nitrogen-containing heterocyclic aromatics are tuned through substituents. We show that substituent position and identity both significantly impact the pK<sub>a</sub><sup>*</sup>. We demonstrate that the substituent effects are additive and identify many disubstituted compounds with substantially greater photobasicity than the most photobasic 5-R quinoline compound identified previously. We show that the addition of a second fused benzene ring to quinoline, along with two electron-donating substituents, lowers the vertical excitation energy into the visible while still maintaining a pK<sub>a</sub><sup>*</sup> > 14. Overall, the structure-function relationships developed in this study provide new insights to guide the development of new photocatalysts that employ photobasicity. </p>

scholarly journals RDX remote Raman detection on NATO SET-237 samples

2021 ◽  
Vol 136 (4) ◽  
Author(s):  
Emanuela C. A. Gallo ◽  
Luca M. L. Cantu ◽  
Frank Duschek
Keyword(s):  
Raman Spectroscopy ◽  
Excitation Energy ◽  
Raman Spectra ◽  
Ccd Camera ◽  
Surface Concentration ◽  
Remote Detection ◽  
Excitation Wavelength ◽  
Standard Samples ◽  
Minimum Requirements

AbstractUltraviolet Raman spectroscopy measurements have been taken at DLR in Lampoldshausen to detect NATO SET-237 standard samples of RDX. The main goal was to quantify the minimum requirements for an unambiguous identification in remote detection (60 cm distance) with a commercial Czerny–Turner spectrometer coupled with a CCD camera. Well-defined distribution of explosives on surfaces was tested as standardized samples. Therefore, Raman spectra of RDX have been acquired for different sample concentrations (50, 250 and 1000 μg/cm2, respectively) and under several laser energies (1.5, 3.0 and 5.0 mJ/pulse, respectively) at 355 nm excitation wavelength. The lowest possible reproducible surface concentration (50 µg/cm2) was detected with excitation energy of 3 mJ/pulse in the described configuration.

Gold Nanorods: From Synthesis to Optical Properties

2014 ◽  
Vol 602-603 ◽  
pp. 993-997
Author(s):  
Gui Jun Ban ◽  
Xiu Li Fu ◽  
Zhi Jian Peng
Keyword(s):  
Optical Properties ◽  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Gold Nanorods ◽  
Plasmon Resonance ◽  
Localized Surface Plasmon ◽  
Excitation Wavelength ◽  
Surface Plasmon Resonance Peak ◽  
Plasmon Resonance Peak ◽  
Aspect Ratios

Gold nanorods with different aspect ratios, exhibiting localized surface plasmon resonance in a tuned longitudinal mode, were prepared by employing a seed mediated growth approach. Their third-order nonlinear optical properties were investigated by using femtosecond Z-scan technique at 800 nm. All the prepared gold nanorods with different aspect ratios exhibited a reverse saturation absorbance behavior, and the value of effective nonlinear absorption coefficient reaches its maximum when the longitudinal surface plasmon resonance peak of the gold nanorods located near the excitation wavelength.

Sign in / Sign up

Export Citation Format

Share Document