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In the interaction of photons using the WinXCom program, the parameters for the three fluorescent molecules, 5NFMOT, 4ATMBC, and 4ATMMC, the effective atomic number (Zeff), and electron density (Nel), have been determined for the energy range of 1–100 GeV using mass attenuation coefficients. The variation of μ/ρ, Zeff , and Nel values for the energies are graphically depicted for different photon interactions. The variation of both parameters, Zeff and Nel , with energy is the same. The significant fluctuation in Zeff and Nel can be attributed to the prevalence of several interaction mechanisms within that energy range. For example, photoelectric absorption takes place at energies lower than 0.01 MeV. Pair formation steadily rises and achieves a constant value at energies above 100 MeV, while Compton scattering starts at 0.01 MeV and continues until it reaches 0.05 MeV. Additionally, kerma (ka) values for a range of energies between 1 keV and 20 MeV have been found. Photoelectric absorption for kerma (ka) seems to be the predominant interaction method for fluorescent compounds. There are biological and therapeutic uses for these Zeff, Nel, and ka values.In the wide energy region, variation of photon interaction parameters with energies has been explained. The presence of several interaction modes in that energy range accounts for the significant variation in Zeff. The primary process of interaction at low energy, or at E < 0.01 MeV, is photoelectric absorption. Within the intermediate energy area, 0.01 MeV < E > 0.05 MeV, Compton scattering is the main interaction mechanism and pair production dominates above at E > 100 MeV. The absorption peak shown by kerma values in the energy range has been detected at 80 keV, where the primary interaction process seems to be photoelectric absorption.

Computational studies on biologically active coumarin derivatives have been studied using Gaussian 16 software. Coumarin molecules with the substitution of benzene and methoxy group Viz., 1IPBC have been used to carry the quantum chemical calculations. Parameters like absorption maxima, oscillator strength and excited state energies, are obtained from UV-Visible absorption maxima. The most practical way for studying optimized geometry is the semi-empirical approach. The DFT approach has been used to study the spectroscopic analysis of NMR, IR, and Raman spectra at the 6-311++G(d, p)/B3LYP basis set. According to the TD-DFT approach, the excited state dipole moment is greater than the ground state dipole moment. The use of IR and Raman vibrational bands facilitates the study of the bending and stretching modes of vibration in the molecule. H1 and C13 NMR shielding values were evaluated from NMR spectra using GIAO method. HOMO-LUMO, MESP map and Mulliken atomic charges give charge distribution within the molecule.

Energy absorption geometric progression (GP) fitting parameters and the corresponding buildup factors have been computed for human organs and tissues, such as adipose tissue, blood (whole), cortical bone, brain (grey/white matter), breast tissue, eye lens, lung tissue, skeletal muscle, ovary, testis, soft tissue, and soft tissue (4‐component), for the photon energy range 0.015–15 MeV and for penetration depths up to 40 mfp (mean free path). The chemical composition of human organs and tissues is seen to influence the energy absorption buildup factors. It is also found that the buildup factor of human organs and tissues changes significantly with the change of incident photon energy and effective atomic number, Zeff. These changes are due to the dominance of different photon interaction processes in different energy regions and different chemical compositions of human organs and tissues. With the proper knowledge of buildup factors of human organs and tissues, energy absorption in the human body can be carefully controlled. The present results will help in estimating safe dose levels for radiotherapy patients and also useful in diagnostics and dosimetry. The tissue‐equivalent materials for skeletal muscle, adipose tissue, cortical bone, and lung tissue are also discussed. It is observed that water and MS20 are good tissue equivalent materials for skeletal muscle in the extended energy range. PACS numbers: 32.80‐t, 87.53‐j, 78.70‐g, 78.70‐Ck

An attempt has been made to calculate the effective atomic number and Kerma for photon energy absorption of organic scintillators in the energy region 1 keV to 20 MeV. We have chosen seven organic scintillators viz., anthracene, stilbene, naphthalene, p -terphenyl, PPO, butyl PBD and PBD. The Z PEA, eff and Kerma values are calculated by using mass-energy absorption coefficient from Hubbell and Seltzer. We also calculated Z PI, eff for total photon interaction with coherent scattering by using WinXCom and compared with the Z PEA, eff.

Effective atomic numbers, electron densities of some vitamins (Retinol, Riboflavin, Niacin, Biotin, Folic acid, Cobalamin, Phylloquinone and Flavonoids) composed of C, H, O, N, Co, P and S have been calculated for total and partial photon interactions by the direct method for energy range 1 keV–100 GeV by using WinXCOM and kinetic energy released in matter (Kerma) relative to air is calculated in energy range of 1 keV–20 MeV. Change in effective atomic number and electron density with energy is calculated for all photon interactions. Variation of photon mass attenuation coefficients with energy are shown graphically only for total photon interaction. It is observed that change in mass attenuation coefficient with composition of different chemicals is very large below 100 keV and moderate between 100 keV and 10 MeV and negligible above 10 MeV. Behaviour of vitamins is almost indistinguishable except biotin and cobalamin because of large range of atomic numbers from 1(H) to 16 (S) and 1(H) to 27(Co) respectively. K a value shows a peak due to the photoelectric effect around K-absorption edge of high- Z constituent of compound for biotin and cobalamin.

Iodinated coumarin derivative 4(3-Iodo-phenoxymethyl)-benzo[h]-chromen-2-one [4(3IP)BC] molecule, which is biologically active in anticancer and anti-tuberculosis properties, was synthesized to study the photophysical properties and the effect of the molecule in polar and nonpolar solvents at room temperature. Experimentally the dipole moments of the ground state and excited state were estimated by the solvatochromic shift method using three independent Lippert’s, Bakhshiev’s, and Kawaski-Chamma-Viallet’s equations. It was found that as the solvent polarity increases, the bathochromic shift occurs, which is a considerable red shift and the excited state dipole moment was greater than that of the ground state dipole moment. The change of dipole moment was 2.43D by the solvatochromic method and 1.49D by the Reichardt microscopic solvent polarity parameter. The solvent effect on spectral characteristics was studied using the Kamlet and Catalan multiple linear regression method. The interactions of the dielectric of the solvent have more influence than hydrogen bonding operations and polarizability, dipolarity and acidity have more influence than basicity. A theoretical computational study was performed with the Gaussian 16W program using the DFT/B3LYP approach. The HOMO-LUMO energies, ESP maps, Mulliken atomic charges, and nonlinear optical properties of the molecule were studied with optimized geometry. The UV-visible spectra with solvents were estimated using TD-DFT and the change in dipole moments was confirms with experimental value.

The effects of solvent on the absorption and emission spectra and dipole moments of the 5ABBM have been extensively studied in a series of solvents. The dipole moments in the excited state are observed to be greater than those in the ground-state in all the solvents studied for the chosen molecule. The dipole moment increase in the excited singlet state ranges from 2.42 to 24.14 D. The experimentally calculated ground state and excited state dipole moments were determined using the solvatochromatic shifts in the absorption and emission spectra as a function of dielectric constant (ɛ) and refractive index (n). These data are used to estimate the excited-state dipole moment using the experimentally determined ground-state dipole moment. A series of fifteen different organic solvents (toluene, methanol, n-butyl alcohol, ethyl acetate, DMS, acetonitrile, benzene, isopropyl alcohol, water, DMF, DCM, DIO, THF, ethanol, and octanol) were investigated at constant dye concentrations. Small changes in the fluorescence spectrum were observed for the different solvents; the highest fluorescence intensity was observed for DMS, and the lowest was observed for water. The Stokes shift in different solvents was studied for the 5ABBM molecule. This results in molecule being more polar in the excited state than in the ground state for the solvents used. The ground state dipole moments, HOMO-LUMO, and molecular electrostatic potential maps were also computed via ab initio calculations and evaluated via Gaussian 09 W software.The effects of solvent on the absorption and emission spectra and dipole moments of the 5ABBM have been extensively studied in a series of solvents. The dipole moments in the excited state are observed to be greater than those in the ground-state in all the solvents studied for the chosen molecule. The dipole moment increase in the excited singlet state ranges from 2.42 to 24.14 D. The experimentally calculated ground state and excited state dipole moments were determined using the solvatochromatic shifts in the absorption and emission spectra as a function of dielectric constant (ɛ) and refractive index (n). These data are used to estimate the excited-state dipole moment using the experimentally determined ground-state dipole moment. A series of fifteen different organic solvents (toluene, methanol, n-butyl alcohol, ethyl acetate, DMS, acetonitrile, benzene, isopropyl alcohol, water, DMF, DCM, DIO, THF, ethanol, and octanol) were investigated at constant dye concentrations. Small changes in the fluorescence spectrum were observed for the different solvents; the highest fluorescence intensity was observed for DMS, and the lowest was observed for water. The Stokes shift in different solvents was studied for the 5ABBM molecule. This results in molecule being more polar in the excited state than in the ground state for the solvents used. The ground state dipole moments, HOMO-LUMO, and molecular electrostatic potential maps were also computed via ab initio calculations and evaluated via Gaussian 09 W software.

The current work uses aniline as a quencher in a variety of solvents to investigate the room-temperature fluorescence quenching of a physiologically active fluorescent probe, namely '6-Methoxy-4-(4-nitro-phenoxy methyl)-chromene-2-one (6MNPM) coumarin molecule'. To understand its behaviour in various media, several solvents with different dielectric constants and refractive indices have been used. Spectroscopy techniques and time-correlated single photon counting were used to describe the absorption spectra, emission spectra, and lifespan value of a molecule. From fluorescence quenching analysis, we find that the S-V curve shows a linear dependence in given solvents with various dielectric values. It is shown that quenching responses are dynamic, many forms of quenching have been identified, and the relevant parameters have been assessed.

The Solvatochromic technique was used to examine the solvent effects of ethyl 5-methyl-3 phenyl-1 H -indole 2-carboxylate [5-MPIC]. Different solvents were used to record 5-MPIC’s absorption and emission spectra at room temperature (300 K). The ground state and excited state dipole moments were estimated experimentally using Lippert’s, Bakshiev’s and Kawaski Chamma Viallet’s equations. The HOMO-LUMO gap and MEP map were also estimated theoretically by using B3LYP/6-31+G (d, p) basis set of Gaussian 16 w program. Dipole moments of excited states reveal a clear polarity difference between the ground and excited states.

Fluorescence quenching of 2-(4'-t-Butylphenyl)-5-(4\"-biphenylyl)-1,3,4-oxadiazole (BPBD) by aniline in toluene has been carried out at room temperature by steady state and time resolved fluorescence spectroscopy. The Stern-Volmer plot by steady state method has been found to be non-linear showing a positive deviation, whereas by time-resolved method it is linear. In order to interpret these results we have used the ground state complex and sphere of action static quenching models. Using these models various rate parameters have been determined. Based on these models, with finite sink approximation model, we conclude that positive deviation Stern-Volmer plot is due to the simultaneous presence of dynamic and static quenching processes.