Time-resolved pulsed-laser Raman studies at the nanosecond level of an aqueous solution of UO2(NO3)2

1982 ◽  
Vol 60 (17) ◽  
pp. 2207-2215 ◽  
Author(s):  
M. Asano ◽  
J. A. Koningstein
Keyword(s):  
Aqueous Solution ◽  
Excited States ◽  
Scattered Light ◽  
Excited Level ◽  
Pulsed Laser ◽  
Population Characteristics ◽  
Optical Pump ◽  
Time Resolved ◽  
Electronic Excited States ◽  
Laser Raman

The pulsed-laser Raman spectrum of aqueous solution of UO2(NO3)2•6H2O is reported. Raman shifts were observed which could be assigned to the v1 mode of the UO2 unit in species (UO2)3(OH),+, (UO2)2(OH)52+, and UO22+. Vibrational ground and excited level transitions were induced, where part of the laser radiation at 22350 cm−1 was used as an optical pump while the remaining part served as Raman probe. The lifetimes of the excited states were 7 μs and 1.5 μs for the trinuclear and dinuclear species, respectively. An analysis of the population characteristics of the ground and electronic excited states of the trinuclear species was performed and compared with the time evolution of the scattered light due to vibrational Raman processes in the ground and electronic excited states

Apparatus for the measurement of the electronic excited-state structure of single crystals using X-ray diffraction

1994 ◽  
Vol 27 (5) ◽  
pp. 727-732 ◽  
Author(s):  
M. A. White ◽  
M. R. Pressprich ◽  
P. Coppens ◽  
D. D. Coppens
Keyword(s):  
Excited States ◽  
Modulation Method ◽  
State Structure ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Electronic Excited States ◽  
Structure Factors ◽  
Counting Statistics ◽  
Mechanical Chopper

Instrumentation for measuring the X-ray diffraction pattern of optically excited crystals is described. The experiment uses a high-power (~1 W) laser and a single-crystal diffractometer equipped with a helium cryostat (T < 70 K). The laser beam is modulated by a mechanical chopper and the diffraction signal gated in synchronization with the chopper phase. The modulation method is capable of observing small changes (down to about 0.01%) in the structure factors upon excitation of a fraction of the molecules in the crystal, given adequate counting statistics. The technique can be used for relatively long lived electronic excited states (τ ≃ 0.1–10 ms). The optical system is also suitable for time-resolved measurements using the time structure of synchrotron radiation.

Cation Effect on the Electronic Excited States of Guanine Nanostructures Studied by Time-Resolved Fluorescence Spectroscopy

2012 ◽  
Vol 116 (27) ◽  
pp. 14682-14689 ◽  
Author(s):  
Ying Hua ◽  
Pascale Changenet-Barret ◽  
Roberto Improta ◽  
Ignacio Vayá ◽  
Thomas Gustavsson ◽  
...  
Keyword(s):  
Fluorescence Spectroscopy ◽  
Excited States ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Electronic Excited States ◽  
Cation Effect

Conditions for excited-state Raman and absorption processes during optical pumping

1981 ◽  
Vol 59 (18) ◽  
pp. 2792-2802 ◽  
Author(s):  
B. Halperin ◽  
J. A. Koningstein
Keyword(s):  
Excited State ◽  
Excited States ◽  
Optical Pumping ◽  
Excited Level ◽  
Tunable Laser ◽  
Laser Wavelength ◽  
Photon Flux ◽  
Optical Pump ◽  
Linear Behaviour ◽  
Transmission Studies

A theoretical analysis is presented for conditions of optical pumping of an electronic excited state and the subsequent induction of Raman scattering thereof, using the radiation of a tunable laser with a specific λ for pumping and Raman probing.The analysis shows that the number of excited states created by the optical pump can be estimated as a function of the photon flux from the (non-linear) behaviour of the transmission of the sample at the selected laser wavelength. It is shown that such transmission studies are a prerequisite before attempts are made to record any excited level Raman spectrum.

Pump-Probe Measurements Using Silicon Nanocrystal Waveguides

2003 ◽  
Vol 770 ◽  
Author(s):  
Nathanael Smith ◽  
Max J. Lederer ◽  
Marek Samoc ◽  
Barry Luther-Davies ◽  
Robert G. Elliman
Keyword(s):  
Probe Beam ◽  
Time Resolution ◽  
Pump Beam ◽  
Silicon Nanocrystals ◽  
Continuous Wave ◽  
Optical Gain ◽  
Optical Pump ◽  
Time Resolved ◽  
Pump Probe ◽  
Probe Measurements

AbstractOptical pump-probe measurements were performed on planar slab waveguides containing silicon nanocrystals in an attempt to measure optical gain from photo-excited silicon nanocrystals. Two experiments were performed, one with a continuous-wave probe beam and a pulsed pump beam, giving a time resolution of approximately 25 ns, and the other with a pulsed pump and probe beam, giving a time resolution of approximately 10 ps. In both cases the intensity of the probe beam was found to be attenuated by the pump beam, with the attenuation increasing monotonically with increasing pump power. Time-resolved measurements using the first experimental arrangement showed that the probe signal recovered its initial intensity on a time scale of 45-70 μs, a value comparable to the exciton lifetime in Si nanocrystals. These data are shown to be consistent with an induced absorption process such as confined carrier absorption. No evidence for optical gain was observed.

Solvent Dependence of Structural Dynamics and Spin-flip Processes in 3,4,5-tri(9H-carbazole-9-yl)benzonitrile (ortho-3CzBN)

2020 ◽  
Author(s):  
Masaki Saigo ◽  
Kiyoshi Miyata ◽  
Hajime Nakanotani ◽  
Chihaya Adachi ◽  
Ken Onda
Keyword(s):  
Dft Calculations ◽  
Excited States ◽  
Structural Changes ◽  
Photophysical Properties ◽  
Delayed Fluorescence ◽  
Time Resolved ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Solvent Dependence ◽  
Acetonitrile Solutions

We have investigated the solvent-dependence of structural changes along with intersystem crossing of a thermally activated delayed fluorescence (TADF) molecule, 3,4,5-tri(9H-carbazole-9-yl)benzonitrile (o-3CzBN), in toluene, tetrahydrofuran, and acetonitrile solutions using time-resolved infrared (TR-IR) spectroscopy and DFT calculations. We found that the geometries of the S1 and T1 states are very similar in all solvents though the photophysical properties mostly depend on the solvent. In addition, the time-dependent DFT calculations based on these geometries suggested that the thermally activated delayed fluorescence process of o-3CzBN is governed more by the higher-lying excited states than by the structural changes in the excited states.<br>

Excited State Tracking During the Relaxation of Coordination Compounds

2018 ◽  
Author(s):  
Juan Sanz García ◽  
Martial Boggio-Pasqua ◽  
Ilaria Ciofini ◽  
Marco Campetella
Keyword(s):  
Excited State ◽  
Excited States ◽  
Potential Energy Surfaces ◽  
Photochemical Reactions ◽  
Complex Nature ◽  
Electronic Excited States ◽  
Ruthenium Nitrosyl ◽  
State Tracking ◽  
Energy Surfaces ◽  
Electronic Wavefunction

<div>The ability to locate minima on electronic excited states (ESs) potential energy surfaces (PESs) both in the case of bright and dark states is crucial for a full understanding of photochemical reactions. This task has become a standard practice for small- to medium-sized organic chromophores thanks to the constant developments in the field of computational photochemistry. However, this remains a very challenging effort when it comes to the optimization of ESs of transition metal complexes (TMCs), not only due to the presence of several electronic excited states close in energy, but also due to the complex nature of the excited states involved. In this article, we present a simple yet powerful method to follow an excited state of interest during a structural optimization in the case of TMC, based on the use of a compact hole-particle representation of the electronic transition, namely the natural transition orbitals (NTOs). State tracking using NTOs is unambiguously accomplished by computing the mono-electronic wavefunction overlap between consecutive steps of the optimization. Here, we demonstrate that this simple but robust procedure works not only in the case of the cytosine but also in the case of the ES optimization of a ruthenium-nitrosyl complex which is very problematic with standard approaches.</div>

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