scholarly journals Theoretical aspects of transient temperature on cubic crystal surface in a photoacoustic effect

2020 ◽  
Vol 99 (3) ◽  
pp. 73-79
Author(s):  
A.P. Sarode ◽  
◽  
O.H. Mahajan ◽  
Keyword(s):  
Integral Transform ◽  
Crystal Surface ◽  
Solid Sample ◽  
Transient Temperature ◽  
Relaxation Processes ◽  
Photoacoustic Cell ◽  
Radiative Relaxation ◽  
Cubic Crystal ◽  
Photoacoustic Effect ◽  
Translational Temperature

In photoacoustic effect, the solid sample absorbs a fraction of the radiation falling upon it and excitation process occurs. The type of excitation depends on the energy of the incident radiation. The relaxation processes, which are also popularly known as non-radiative de-excitation processes generally take place. The light – matter interaction is responsible for the generation of heat within the solid sample. The temperature of the sample changes due to absorption and non-radiative relaxation by the atoms. The pressure fluctuations will be generated due to the heating and cooling of the sample. Today, crystalline solids are widely studied due to their wide scientific and industrial applications. Temperature is one of the important parameter to be studied regarding artificial preparation of large crystals. In this paper, transient translational temperature on the surface of a homogeneous isotropic cubic crystal kept in a photoacoustic cell is calculated theoretically. For a simple cubic homogeneous crystal kept in a photoacoustic cell, an airy stress function is determined based on laser interaction with surface of the crystal. By applying the finite Marchi-Fasulo integral transform method within the crystal size limitations, transient translational temperature is exactly determined.

Displacement fields of a Cuboid crystal in a Photoacoustic Cell: Mathematical aspects

2021 ◽  
Vol 101 (1) ◽  
pp. 6-11
Author(s):  
A.P. Sarode ◽  
◽  
O.H. Mahajan ◽  
Keyword(s):  
Displacement Field ◽  
Thermal Stresses ◽  
Integral Transform ◽  
Solid State Physics ◽  
Photoacoustic Cell ◽  
Displacement Fields ◽  
Transform Method ◽  
Premature Failure ◽  
Acoustic Effect ◽  
Photoacoustic Effect

Photo acoustic effect is popular due to a minimal sample preparation during execution, the ability to examine scattering and opaque sample along with the capability to access depth profile. These features enable Photoacoustic spectroscopy to be used in depth-resolved characterization of solids. Thermal interaction is a basic perspective in solid state physics research regarding industrial devices and components. It is a key factor of fabrication and performance of such devices and components. Today, crystalline solids are widely studied due to their wide scientific and industrial applications. Displacement field resulting in thermal stresses is one of the important aspects of premature failure of industrial components and devices. In this paper, displacement fields in photoacoustic effect with solid cuboid crystal are mathematically presented. According to our opinion, displacement fields in photoacoustic effect in three dimensional analysis are not reported earlier. Hence that will be a major contribution of this paper. For a simple cuboid homogeneous crystal kept in a photoacoustic cell, an airy stress function is determined based on laser interaction with surface of the crystal. By applying the finite Marchi-Fasulo integral transform method within the crystal size limitations, displacement field is exactly determined.

scholarly journals Photoacoustic trace detection of gases at the parts-per-quadrillion level with a moving optical grating

2017 ◽  
Vol 114 (28) ◽  
pp. 7246-7249 ◽  
Author(s):  
Lian Xiong ◽  
Wenyu Bai ◽  
Feifei Chen ◽  
Xian Zhao ◽  
Fapeng Yu ◽  
...  
Keyword(s):  
Sound Speed ◽  
Photoacoustic Signal ◽  
Laser Resonator ◽  
Trace Detection ◽  
Photoacoustic Cell ◽  
Optical Source ◽  
Photoacoustic Effect ◽  
One Dimensional ◽  
Optical Grating ◽  
Detector Crystal

The amplitude of the photoacoustic effect for an optical source moving at the sound speed in a one-dimensional geometry increases linearly in time without bound in the linear acoustic regime. Here, use of this principle is described for trace detection of gases, using two frequency-shifted beams from a CO2 laser directed at an angle to each other to give optical fringes that move at the sound speed in a cavity with a longitudinal resonance. The photoacoustic signal is detected with a high-Q, piezoelectric crystal with a resonance on the order of 443 kHz. The photoacoustic cell has a design analogous to a hemispherical laser resonator and can be adjusted to have a longitudinal resonance to match that of the detector crystal. The grating frequency, the length of the resonator, and the crystal must all have matched frequencies; thus, three resonances are used to advantage to produce sensitivity that extends to the parts-per-quadrillion level.

Ultrafast Radiative Relaxation Processes in Multication Cross-Luminescence Materials

2020 ◽  
Vol 67 (6) ◽  
pp. 1009-1013
Author(s):  
Juhan Saaring ◽  
Eduard Feldbach ◽  
Vitali Nagirnyi ◽  
Sergey Omelkov ◽  
Alexander Vanetsev ◽  
...  
Keyword(s):  
Relaxation Processes ◽  
Radiative Relaxation

Electronic sputtering of solid N2 and O2: A comparison of non-radiative relaxation processes

1985 ◽  
Vol 164 (2-3) ◽  
pp. A737
Author(s):  
Frederick L. Rook ◽  
Robert E. Johnson ◽  
Walter L. Brown
Keyword(s):  
Relaxation Processes ◽  
Radiative Relaxation ◽  
Solid N2

Non-radiative relaxation processes of the Pr3+ ion

1995 ◽  
Vol 62 (4) ◽  
pp. 664-670 ◽  
Author(s):  
C. de Mello Donega ◽  
A. Meijerink ◽  
G. Blasse
Keyword(s):  
Relaxation Processes ◽  
Radiative Relaxation

scholarly journals On Anomalous Fluorescence of Symmetrical Polymethine Dyes

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
P. O. Kondratenko ◽  
Yu. M. Lopatkin
Keyword(s):  
Excited States ◽  
Ground State ◽  
Internal Conversion ◽  
Polymethine Dyes ◽  
Necessary Condition ◽  
Relaxation Processes ◽  
Sufficient Condition ◽  
Radiative Relaxation ◽  
Higher Excited States ◽  
Group Theoretical Analysis

The group-theoretical analysis of polymethine dyes (PMD) showed that relaxation processes between the states S3 and S1 are forbidden, either by radiation or by internal conversion. From the state S3, only transition to the ground state of the molecule is possible. Since the experimental data state that the quantum yield of S3 ⟶ S0 fluorescence does not exceed 1%, it is indicated that the internal conversion rate can be 2 orders of magnitude higher than the radiative relaxation rate of the molecule. Concerning the reasons for the appearance of fluorescence from the higher excited states of molecules, it can be asserted that the necessary condition for the appearance of S3 ⟶ S0 fluorescence is the absence of S0 ⟶ S1(v)-absorption in the region of the S0 ⟶ S3 transition. The sufficient condition is the corresponding symmetry of the excited states, which imposes a prohibition on the S3 ⟶ S1 relaxation process.

Structure and excited state properties of multiporphyrin arrays formed by supramolecular design

2003 ◽  
Vol 07 (11) ◽  
pp. 731-754 ◽  
Author(s):  
Eduard I. Zenkevich ◽  
Christian von Borczyskowski ◽  
Alexander M. Shulga
Keyword(s):  
Excited State ◽  
Photoinduced Electron Transfer ◽  
Spectral Properties ◽  
Photophysical Properties ◽  
Covalent Binding ◽  
Relaxation Processes ◽  
Radiative Relaxation ◽  
Time Resolved ◽  
Chemical Dimers ◽  
Femtosecond Time Scale

Structurally defined nanoscale self-assembled multiporphyrin arrays of variable geo-metry and composition (up to eight tetrapyrrole macrocycles) have been formed via two-fold extra-ligation in solutions at 77-293 K. The array formation is based on non-covalent binding interactions of the phenyl bridged Zn octaethylporphyrin chemical dimers or trimers, ( ZnOEP )2 Ph or ( ZnOEP )3 Ph 2, with di- and tetrapyridyl substituted tetrapyrrole extra-ligands (porphyrin, pentafluorophenyl substituted porphyrin, Cu porphyrin, tetrahydroporphyrin). Using steady-state and time-resolved measurements, spectral properties as well as pathways and dynamics of non-radiative relaxation processes (energy migration, photoinduced electron transfer, exchange d-π effects, realized in nano-femtosecond time scale) have been studied in these complexes upon variation of the composition, mutual geometry, redox and photophysical properties of interacting subunits as well as on the tempera-ture and polarity of surrounding.

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