Photoelectron Spectroscopy in Molecular Physical Chemistry

2022 ◽  
Author(s):  
Ingo Fischer ◽  
Stephen T Pratt
Keyword(s):  
Physical Chemistry ◽  
Charged Particle ◽  
Electron Energy ◽  
Energy Resolution ◽  
Photoelectron Spectroscopy ◽  
Powerful Method ◽  
Molecular Physics ◽  
Particle Imaging

Photoelectron spectroscopy has long been a powerful method in the toolbox of experimental physical chemistry and molecular physics. Recent improvements in coincidence methods, charged-particle imaging, and electron energy resolution have...

Parallel Detection of Electron Energy Loss Spectra in Direct Mode

1990 ◽  
Vol 48 (2) ◽  
pp. 82-83
Author(s):  
Eckhard Quandt ◽  
Stephan laBarré ◽  
Andreas Hartmann ◽  
Heinz Niedrig
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Energy Resolution ◽  
Large Angle ◽  
Maximum Energy ◽  
Semiconductor Detectors ◽  
Parallel Detection ◽  
Photodiode Arrays ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

Due to the development of semiconductor detectors with high spatial resolution -- e.g. charge coupled devices (CCDs) or photodiode arrays (PDAs) -- the parallel detection of electron energy loss spectra (EELS) has become an important alternative to serial registration. Using parallel detection for recording of energy spectroscopic large angle convergent beam patterns (LACBPs) special selected scattering vectors and small detection apertures lead to very low intensities. Therefore the very sensitive direct irradiation of a cooled linear PDA instead of the common combination of scintillator, fibre optic, and semiconductor has been investigated. In order to obtain a sufficient energy resolution the spectra are optionally magnified by a quadrupole-lens system.The detector used is a Hamamatsu S2304-512Q linear PDA with 512 diodes and removed quartz-glas window. The sensor size is 13 μm ∗ 2.5 mm with an element spacing of 25 μm. Along with the dispersion of 3.5 μm/eV at 40 keV the maximum energy resolution is limited to about 7 eV, so that a magnification system should be attached for experiments requiring a better resolution.

DEVELOPMENT OF A CONICAL ENERGY ANALYZER FOR ANGLE-RESOLVED PHOTOELECTRON SPECTROSCOPY

2002 ◽  
Vol 09 (01) ◽  
pp. 583-586
Author(s):  
KOTA IWASAKI ◽  
KOICHIRO MITSUKE
Keyword(s):  
Gas Phase ◽  
Energy Resolution ◽  
Photoelectron Spectroscopy ◽  
Angular Resolution ◽  
Photoelectron Spectra ◽  
Sensitive Detector ◽  
Energy Analyzer ◽  
Position Sensitive ◽  
Pass Energy ◽  
Helium Discharge

A new angle-resolving electron energy analyzer composed of a conical electrostatic prism and a position-sensitive detector was developed for gas phase photoelectron spectroscopy. The performance of the analyzer has been tested by measuring photoelectron spectra of Ar using a helium discharge lamp. The angular resolution of 3° was achieved at the pass energy E of 5.6 eV. The best energy resolution was ΔE/E = 0.043 at E = 1.4 eV .

7. Investigating matter

2014 ◽  
pp. 106-120
Author(s):  
Peter Atkins
Keyword(s):  
Physical Chemistry ◽  
Organic Chemistry ◽  
Mass Spectrometry ◽  
Nuclear Magnetic Resonance ◽  
Quantum Mechanics ◽  
Magnetic Resonance ◽  
Photoelectron Spectroscopy ◽  
Tunnelling Microscopy ◽  
Investigative Technique

Physical chemistry lies at the heart of one of chemistry's principal applications and achievements: the identification of the substances present in a sample and the determination of their abundances and structures. ‘Investigating matter’ considers how the laser and computer have elaborated and refined classical techniques. Various forms of investigative technique are explained including absorption spectroscopy and nuclear magnetic resonance. Mass spectrometry is widely used in organic chemistry to help identify compounds and photoelectron spectroscopy is used both to explore the energies with which electrons are bound inside molecules and to identify species on surfaces. The study of surfaces has been transformed by scanning tunnelling microscopy, which relies on quantum mechanics.

A New High Performance Electron Energy Loss Spectrometer for use with Monochromated Microscopes

2001 ◽  
Vol 7 (S2) ◽  
pp. 908-909
Author(s):  
H.A. Brink ◽  
M. Barfels ◽  
B. Edwards ◽  
P. Burgner
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Energy Resolution ◽  
Optical Design ◽  
Electron Source ◽  
High Voltage Power Supply ◽  
Electron Energy Loss Spectrometer ◽  
Electron Microscopes ◽  
Electron Energy Loss ◽  
Better Than

A new type of electron energy loss spectrometer for use with monochromated microscopes is presented. The energy resolution of the spectrometer is better than 0.100 eV. A completely new electron optical design with a number of extra optical elements and advanced tuning software makes it possible to correct spectrum aberrations to 4th order, which increases sensitivity and collection angles. New high-stability electronics make it possible to maintain energy resolution over a period of several minutes in a practical laboratory environment.The energy resolution of Transmission Electron Microscopes (TEMs) equipped with electron energy loss spectrometers is determined by a combination of the energy spread of the electron source, the stability of the microscope’s high voltage power supply, and the energy resolution of the spectrometer. Commercial microscopes usually employ electron sources with an energy distributions of around 0.5 eV or more (FWHM), limiting the energy ultimate energy resolution that can be achieved. Recently FEI constructed a special 200 kV TEM with a built-in monochromator which makes it possible to monochromize the electron source to better than 0.100 eV. A prototype of the presented spectrometer has been installed on this microscope.

Using Electron Energy-Loss Spectroscopy (EELS) To Study Rare Earth Elements In Natural Crystals

2000 ◽  
Vol 6 (S2) ◽  
pp. 206-207
Author(s):  
Huifang Xu
Keyword(s):  
Rare Earth ◽  
Energy Loss ◽  
Rare Earth Elements ◽  
Electron Energy ◽  
Energy Resolution ◽  
Electron Energy Loss Spectroscopy ◽  
Relative Concentration ◽  
Chemical Properties ◽  
Similar Chemical ◽  
Electron Energy Loss

Because of similar chemical properties of the rare earth elements (Ree), whole series of the Ree may occur in natural Ree-bearing crystals. Relative concentration of the Ree may vary as the crystallization environments change. Electron energy-dispersive spectroscopy (EDS) associated with TEM is unable to resolve Ree and other coexistence elements, such as Ba nd Ti, because of peak overlap and energy resolution (∼ 150 eV) of EDS. Figure A indicate multiple peaks from Ce only. The Cu peaks are from Cu grid holding the specimen. Electron energy-loss spectroscopy (EELS) with energy resolution of < 1 eV is able to resolve all Ree in natural Ree-bearing crystals.Natural carbonate crystals from a Ree ore deposit were investigated by using EELS associated with field emission-gun (FEG) TEM. The crystals are in a chemical series of BaCO3 - Ree(CO3)F [1]. In Figure B, EEL spectra A and B are from Ce-rich and La-rich bastnaesite (Ree(CO3)F), respectively; spectrum D is from cordylite (BaCO3 (Ree(CO3)F); spectrum E is from huanghoite (BaCO3 Ree(CO3)F), spectrum F is from BaCO3; spectrum C is from an unknown Ree-rich phase.

scholarly journals Charge Transfer in Dimer with Dissipation

2019 ◽  
Vol 224 ◽  
pp. 03006
Author(s):  
Nadezhda Fialko ◽  
Maxim Olshevets ◽  
Victor Lakhno
Keyword(s):  
Charge Transfer ◽  
Charged Particle ◽  
Computer Modeling ◽  
Electron Energy ◽  
Small Radius ◽  
Memory Devices ◽  
Charge Motion ◽  
Transfer Processes ◽  
Holstein Model ◽  
Charge Tunneling

The study of the charge transfer processes in biomacromolecules such as DNA is essential for the development of nanobioelectronics, design and construction of DNA-based nanowires, memory devices, logical elements, etc. Mathematical and computer modeling of charge transfer in biopolymer chains is an important part of these investigations. Some properties of charge transfer can be demonstrated by modeling of two-site chain. Based on the semi-classical Holstein model we consider a system of two sites and charged particle (electron or hole) in which the oscillations of the first site are not related to the charge motion, and the parameters of the second site correspond to a small-radius polaron. The system steady states depending on the electron energy H at the second site are studied numerically. The dynamics of the charge initially localized at the first site is modeled. Various modes depending on H are demonstrated: charge tunneling, resonant transfer, and lack of transfer.

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