Calculation of reliable non-resonant Kα X-ray emission spectra of organic molecules and other small molecules

2020 ◽  
Vol 98 (12) ◽  
pp. 741-745
Author(s):  
Delano P. Chong
Keyword(s):  
Small Molecules ◽  
Gas Phase ◽  
Organic Molecules ◽  
Simple Procedure ◽  
Emission Spectra ◽  
Matrix Elements ◽  
X Ray ◽  
Valence Electrons ◽  
The Difference ◽  
Vertical Ionization Energies

For reliable calculation of vertical ionization energies (VIEs) of both core and valence electrons of gas-phase organic molecules and other small molecules, we developed DFT procedures in 1999 and 2009. The difference between core and valence VIEs give the energies for X-ray emission spectra (XES). The dipole matrix elements between core and valence electrons required for calculation of the XES intensities are now easily available. The simple procedure for calculation of reliable XES is demonstrated by comparison with known XES for H2O(g), NH3(g), CO(g), CO2(g), N2(g), and NNO(g). Consequently, the XES of H2CO(g), formamide(g), 1-nitrosamine(g), N-methylformamide(g), 1-nitrosoaziridine(g), and oxirane(g) are predicted with confidence.

HIGH RESOLUTION L X-RAY EMISSION SPECTRA OF Fe AND Cu INDUCED BY O.75 MeV/u ION IMPACT

1995 ◽  
Vol 05 (02n03) ◽  
pp. 203-209 ◽  
Author(s):  
H. KAGEYAMA ◽  
R. TAKAHASHI ◽  
D. HAMAGUCHI ◽  
T. AWATA ◽  
T. NAKAE ◽  
...  
Keyword(s):  
High Resolution ◽  
Lower Energy ◽  
Emission Spectra ◽  
Crystal Spectrometer ◽  
Transition Energies ◽  
X Ray ◽  
The Difference ◽  
Ion Impact ◽  
Electron Vacancy ◽  
Good Agreement

High resolution L x-ray emission spectra of Fe and Cu have been measured by 0.75 MeV/u H and He, and 0.73 MeV/u He, Si and Ar ion impacts with a crystal spectrometer. The x-ray transition energies in the Fe and Cu targets for Lι, Lη, Lα1,2, Lβ1 and Lβ3,4 diagram lines induced by light ion impacts are determined, which are in good agreement with those given in the reference. The difference in L x-ray emission spectra produced by H, He, Si and Ar ions is considered and the emission spectra for the Cu target are compared with the calculated ones based on the multiconfiguration Dirac-Fock method. The origin of the broadening of the Lα1,2 line to the lower energy for Si and Ar ion impacts is attributed to one 2p plus one 3d electron vacancy production.

scholarly journals The soft X-ray spectroscopy of solids, II. Emission spectra from simple chemical compounds

1940 ◽  
Vol 176 (965) ◽  
pp. 229-262 ◽  
Keyword(s):  
Emission Spectra ◽  
Negative Ions ◽  
Chemical Compounds ◽  
Polar Compounds ◽  
Energy Scale ◽  
X Ray ◽  
Valence Electrons ◽  
Simple Chemical ◽  
Solid Form ◽  
Difficult Subject

K - and L -emission bands, emitted in the soft X -ray region of the spectrum by atoms in a number of chemical compounds, have been investigated. The substances for which such spectra are available through the present or previous work are: fluorides, chlorides, bromides, iodides; oxides, sulphides; boron nitride and other boron com pounds; and carbides. In the cases of SiC, BN and a number of oxides, spectra from both the component atom s forming the com pound have been obtained. The results are interpreted, as those for metals and element-insulators have been in a previous paper (Skinner 1940), to give the characteristics of the bands of levels which exist for the valence-electrons in the normal state of the substance. In the case of the halides, data on the p - and s -levels of the negative ions are given, and it is shown that, even in this case, the crystal structure leaves its mark on the form of the bands of levels. The 2 p -bands of oxygen from most oxides are more spread-out on an energy scale, thus showing that the interaction between electrons in neighbouring atoms is considerable. The spectra of the metal ions in oxides are very complex, and an attempt is made to disentangle the factors which lead to this complication. In doing so, it is hoped that we may have thrown some light on the difficult subject of the structure of semi-polar compounds in solid form.

X-ray emission spectra of small molecules

1975 ◽  
Vol 272 (2) ◽  
pp. 131-141 ◽  
Author(s):  
L. O. Werme ◽  
J. Nordgren ◽  
H. �gren ◽  
C. Nordling ◽  
K. Siegbahn
Keyword(s):  
Small Molecules ◽  
Emission Spectra ◽  
X Ray

Schemes to determine the crystal potential under dynamical conditions using voltage variation

1999 ◽  
Vol 55 (2) ◽  
pp. 160-167 ◽  
Author(s):  
Peter Rez
Keyword(s):  
Simple Procedure ◽  
Relativistic Effects ◽  
Single Scattering ◽  
High Energy ◽  
Dynamical Diffraction ◽  
X Ray ◽  
Crystal Potential ◽  
Voltage Variation ◽  
High Energy Electrons ◽  
The Difference

Charge densities and crystal structures can be determined routinely from X-ray diffraction as X-ray scattering is relatively weak and single scattering can be assumed. The strong dynamical diffraction of high-energy electrons has prevented electron diffraction from being used in the same way. Dynamical diffraction describes both the propagation of the Bragg diffracted wave in the crystal and the scattering by the crystal potential. The balance between these two processes changes as a function of voltage due to relativistic effects. The difference in diffracted intensities recorded at two voltages is shown to be directly proportional to the crystal potential. This is confirmed by calculations using first-order perturbation theory which show negligible differences compared to exact calculation. It should therefore be possible to use differences in intensity measured as a function of voltage to determine the crystal potential directly. If the full complex wave function is available, then there is a particularly simple procedure to recover the potential, even under dynamical conditions.

X-RAY EMISSION AND ABSORPTION SPECTRA AND ELECTRONIC STRUCTURE OF MgB2

2002 ◽  
Vol 09 (02) ◽  
pp. 1097-1102
Author(s):  
E. Z. KURMAEV ◽  
I. I. LYAKHOVSKAYA ◽  
J. KORTUS ◽  
M. DEMETER ◽  
M. NEUMANN ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Charge Transfer ◽  
Binding Energy ◽  
Emission Spectra ◽  
Energy Scale ◽  
Matrix Elements ◽  
X Ray ◽  
Emission And Absorption Spectra ◽  
Binding Energy Scale ◽  
Good Agreement

Measurements of X-ray emission and absorption of the constituents of MgB 2 are presented. The results obtained are in good agreement with calculated X-ray spectra, with dipole matrix elements taken into account. The comparison of X-ray emission spectra of graphite, AlB 2, and MgB 2 in the binding energy scale supports the idea of charge transfer from σ to π bands, which creates holes at the top of the bonding σ bands and drives the high-Tc superconductivity in MgB 2.

Composite host lattices of 4,4′-sulfonyldibenzoate water/boric acid in two tetrapropylammonium inclusion compounds

2018 ◽  
Vol 74 (9) ◽  
pp. 1026-1031
Author(s):  
Xiangxiang Wu ◽  
Huahui Zeng ◽  
Yunxia Yang
Keyword(s):  
Boric Acid ◽  
Small Molecules ◽  
Crystal Structures ◽  
Inclusion Compounds ◽  
X Ray Diffraction ◽  
X Ray ◽  
Counter Ions ◽  
Proton Donors ◽  
The Difference ◽  
Host Lattices

Two novel inclusion compounds of 4,4′-sulfonyldibenzoate anions and tetrapropylammonium cations with different ancillary molecules of water and boric acid, namely bis(tetrapropylammonium) 4,4′-sulfonyldibenzoate dihydrate, 2C12H28N+·C14H8O6S2−·H2O (1), and bis(tetrapropylammonium) 4,4′-sulfonyldibenzoate bis(boric acid), 2C12H28N+·C14H8O6S2−·2H3BO3 (2), were prepared and characterized using single-crystal X-ray diffraction. In the two salts, the host 4,4′-sulfonyldibenzoic acid molecules, which are converted to the corresponding anions under basic conditions, can be regarded as proton acceptors which link different proton donors of the ancillary molecules of water or boric acid. In this way, an isolated hydrogen-bonded tetramer is constructed in salt 1 and a ribbon is constructed in salt 2. The tetramers and ribbons are then packed in a repeating manner to generate various host frameworks, and the tetrapropylammonium guest counter-ions are contained in the cavities of the host lattices to give the final stable crystal structures. In these two salts, although the host anion and guest cation are the same, the difference in the ancillary small molecules results in different structures, indicating the significance of ancillary molecules in the formation of crystal structures.

Primary photoprocesses of chlorophyll and related molecule

1963 ◽  
Vol 157 (968) ◽  
pp. 293-300 ◽  
Keyword(s):  
Small Molecules ◽  
Gas Phase ◽  
Organic Molecules ◽  
Vibrational Energy ◽  
Electronic States ◽  
Photochemical Reactions ◽  
Apparent Paradox ◽  
Related Molecule ◽  
Conjugated Organic Molecules ◽  
Photochemical Properties

Although the system in which photosynthesis occurs is exceedingly complex there is no reason to suppose that the primary processes involve any principles not already encountered in the photochemistry of other large organic molecules. It will therefore be useful to consider such processes with reference to chlorophyll as a particular case. In many ways the luminescent and photochemical properties of large conjugated organic molecules in the condensed phase are simpler than those of small molecules or molecules in the gas phase. This apparent paradox is a result of the rapid dissipation of excess vibrational energy and the rapid inter-conversion between electronic states which occurs in such systems. An additional simplification is introduced when only processes relevant to photosynthesis need to be considered since irreversible photochemical reactions are then unimportant. Most of the detailed information which is available refers to dilute solutions where the solute molecules are monomeric, though they may be complexed with the solvent, and it will be convenient to consider such systems first.

Microcalorimeter EDS Measurements of Chemical Shifts in Fe Compounds

1998 ◽  
Vol 4 (S2) ◽  
pp. 196-197 ◽  
Author(s):  
D. A. Wollman ◽  
Dale E. Newbury ◽  
G. C. Hilton ◽  
K. D. Irwin ◽  
L. L. Dulcie ◽  
...  
Keyword(s):  
Chemical Shifts ◽  
Energy Dispersive Spectrometer ◽  
Emission Spectra ◽  
High Energy ◽  
Peak Position ◽  
Binding Energies ◽  
High Energy Resolution ◽  
X Ray ◽  
Valence Electrons ◽  
Electron Binding Energies

We report measurements of chemical shifts in the Fe-L x-ray lines of different Fe compounds from xray emission spectra acquired using a microcalorimeter energy dispersive spectrometer (EDS). The observed changes in peak position and relative intensity of the Fe-L x-ray lines are in agreement with measurements obtained using a wavelength dispersive spectrometer (WDS), demonstrating the usefulness of microcalorimeter EDS for high-energy-resolution x-ray microanalysis.Chemical shifts result from changes in electron binding energies with the chemical environment of atoms. In x-ray spectra, chemical shifts lead to changes in x-ray peak positions, relative peak intensities, and peak shapes. These chemical bonding effects can be significant (with x-ray peak shifts on the order of 1 eV), particularly for x-ray lines resulting from transitions involving valence electrons of light elements such as B and C.

scholarly journals X-ray processing of a realistic ice mantle can explain the gas abundances in protoplanetary disks

2020 ◽  
Vol 117 (28) ◽  
pp. 16149-16153
Author(s):  
Angela Ciaravella ◽  
Guillermo M. Muñoz Caro ◽  
Antonio Jiménez-Escobar ◽  
Cesare Cecchi-Pestellini ◽  
Li-Chieh Hsiao ◽  
...  
Keyword(s):  
Gas Phase ◽  
Organic Molecules ◽  
Protoplanetary Disks ◽  
Abundant Species ◽  
X Rays ◽  
X Ray ◽  
Solar Systems ◽  
Detailed Observation ◽  
Solar Type ◽  
Complex Organic

The Atacama Large Millimeter Array has allowed a detailed observation of molecules in protoplanetary disks, which can evolve toward solar systems like our own. While CO,CO2, HCO, andH2COare often abundant species in the cold zones of the disk,CH3OHorCH3CNare only found in a few regions, and more-complex organic molecules are not observed. We simulate, experimentally, ice processing in disks under realistic conditions, that is, layered ices irradiated by soft X-rays. X-ray emission from young solar-type stars is thousands of times brighter than that of today’s sun. The ice mantle is composed of aH2O:CH4:NH3mixture, covered by a layer made ofCH3OHand CO. The photoproducts found desorbing from both ice layers to the gas phase during the irradiation converge with those detected in higher abundances in the gas phase of protoplanetary disks, providing important insights on the nonthermal processes that drive the chemistry in these objects.

Preparation and study of the bacterial nanocellulose properties

2021 ◽  
pp. 120-130
Author(s):  
V. Boyko ◽  
◽  
V. Chornii ◽  
S. Nedilko ◽  
V. Scherbatskyi ◽  
...  
Keyword(s):  
Raw Materials ◽  
Emission Spectra ◽  
Luminescence Spectroscopy ◽  
Chemical Methods ◽  
Alternative Source ◽  
Bacterial Nanocellulose ◽  
X Ray ◽  
Manufacturing Method ◽  
The Difference ◽  
Diffraction Patterns

Nanocellulose is a biopolymer that due to its attractive physicochemical properties has been intensively studied as a material for use in biomedicine, food industry, electronics etc. Modern chemical methods of nanocellulose production from wood raw materials require the use of acids, alkalis and solvents. This is a disadvantage from both economic and environmental points of view. The biomass that is obtained as a result of microbial processes can be regarded as an alternative source of nanocellulose. This paper deals with the application of the method based on Kombucha membranes for the preparation of bacterial nanocellulose. The structure and optical properties of the obtained films of bacterial nanocellulose have been studied by X-ray diffraction analysis and luminescence spectroscopy. The difference in the sizes of the regions on which X-ray scattering occurs was established from the analysis of diffraction patterns of nanocellulose films obtained by microbial and chemical methods. These regions are much larger in the case of bacterial nanocellulose. The redistribution of the peaks intensity in the diffraction patterns with a change in the manufacturing method reflects, probably, the difference in the ratio between crystalline and amorphous content for cellulose samples of various types. Samples of bacterial cellulose both "pure" and with the addition of the Rhodamine C dye are characterized by intense visible photoluminescence at room temperature. The treatment of samples with a NaOH solution leads to a decrease in the intensity of the red band (with a maximum at 670 nm) of cellulose luminescence, while the addition of a dye enhances the band in the yellow (maximum at 570 nm) spectral range. Thus, the method used in this work to made bacterial nanocellulose makes it possible to create luminescent films which emission spectra can be easily modified with alkalis or dyes treatment.

Sign in / Sign up

Export Citation Format

Share Document