Enhanced a High Vacuum Pressure Inside a Fixed Anode X-ray Tube Equipped with a Nonproliferation Getter

2013 ◽  
Vol 63 (1) ◽  
pp. 113-120
Author(s):  
Chang Sil JANG ◽  
Rae Jun PARK ◽  
Sang Suk LEE*
Keyword(s):  
High Vacuum ◽  
Vacuum Pressure ◽  
X Ray

Detector strategies for environmental scanning electron microscopy

1992 ◽  
Vol 50 (2) ◽  
pp. 1296-1297
Author(s):  
Klaus-Ruediger Peters
Keyword(s):  
High Vacuum ◽  
Environmental Scanning Electron Microscopy ◽  
Charge Carriers ◽  
Environmental Scanning ◽  
Surface Information ◽  
X Ray ◽  
Detector Electrode ◽  
Electrons And Ions ◽  
Low Energy Electrons ◽  
Environmental Sem

Environmental SEM operate at specimen chamber pressures of ∼20 torr (2.7 kPa) allowing stabilization of liquid water at room temperature, working on rugged insulators, and generation of an environmental secondary electron (ESE) signal. All signals available in conventional high vacuum instruments are also utilized in the environmental SEM, including BSE, SE, absorbed current, CL, and X-ray. In addition, the ESEM allows utilization of the flux of charge carriers as information, providing exciting new signal modes not available to BSE imaging or to conventional high vacuum SEM.In the ESEM, at low vacuum, SE electrons are collected with a “gaseous detector”. This detector collects low energy electrons (and ions) with biased wires or plates similar to those used in early high vacuum SEM for SE detection. The detector electrode can be integrated into the first PLA or positioned at any other place resulting in a versatile system that provides a variety of surface information.

Electron behavior in the gaseous environment of the ESEM chamber

1996 ◽  
Vol 54 ◽  
pp. 838-839 ◽  
Author(s):  
S.A. Wight
Keyword(s):  
Secondary Electron ◽  
High Vacuum ◽  
Beam Current ◽  
Chamber Pressure ◽  
Environmental Scanning ◽  
Carbon Block ◽  
Faraday Cup ◽  
X Ray ◽  
Gaseous Environment ◽  
Working Distance

Measurements of electrons striking the sample in the Environmental Scanning Electron Microscope (ESEM) are needed to begin to understand the effect of the presence of the gas on analytical measurements. Accurate beam current is important to x-ray microanalysis and it is typically measured with a faraday cup. A faraday cup (Figure 1) was constructed from a carbon block embedded in non-conductive epoxy with a 45 micrometer bore platinum aperture over the hole. Currents were measured with an electrometer and recorded as instrument parameters were varied.Instrument parameters investigated included working distance, chamber pressure, condenser percentage, and accelerating voltage. The conditions studied were low vacuum with gaseous secondary electron detector (GSED) voltage on; low vacuum with GSED voltage off; and high vacuum (GSED off). The base conditions were 30 kV, 667 Pa (5 Torr) water vapor, 100,000x magnification with the beam centered inside aperture, GSED voltage at 370 VDC, condenser at 50%, and working distance at 19.5 mm. All modifications of instrument parameters were made from these conditions.

The Growth and Characterization of Germanium-Carbon Alloy Thin Films

1992 ◽  
Vol 270 ◽  
Author(s):  
Haojie Yuan ◽  
R. Stanley Williams
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Vacuum Chamber ◽  
Optical Band Gap ◽  
High Vacuum ◽  
Optical Absorption Spectroscopy ◽  
Alloy Thin Film ◽  
New Materials ◽  
X Ray

ABSTRACTThin films of pure germanium-carbon alloys (GexC1−x with x ≈ 0.0, 0.2, 0.4, 0.5, 0.6, 0.8, 1.0) have been grown on Si(100) and A12O3 (0001) substrates by pulsed laser ablation in a high vacuum chamber. The films were analyzed by x-ray θ-2θ diffraction (XRD), x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), conductivity measurements and optical absorption spectroscopy. The analyses of these new materials showed that films of all compositions were amorphous, free of contamination and uniform in composition. By changing the film composition, the optical band gap of these semiconducting films was varied from 0.00eV to 0.85eV for x = 0.0 to 1.0 respectively. According to the AES results, the carbon atoms in the Ge-C alloy thin film samples has a bonding configuration that is a mixture of sp2 and sp3 hybridizations.

Recent Developments In Monochromatic Microprobe X-Ray Fluorescence (MMXRF)

1998 ◽  
Vol 4 (S2) ◽  
pp. 378-379
Author(s):  
Z. W. Chen ◽  
D. B. Wittry
Keyword(s):  
Materials Science ◽  
High Vacuum ◽  
Three Dimensional ◽  
High Sensitivity ◽  
X Rays ◽  
Fluorescence Excitation ◽  
X Ray ◽  
Quantitative Microanalysis ◽  
Recent Developments ◽  
Fifth Order

A monochromatic x-ray microprobe based on a laboratory source has recently been developed in our laboratory and used for fluorescence excitation. This technique provides high sensitivity (ppm to ppb), nondestructive, quantitative microanalysis with minimum sample preparation and does not require a high vacuum specimen chamber. It is expected that this technique (MMXRF) will have important applications in materials science, geological sciences and biological science.Three-dimensional focusing of x-rays can be obtained by using diffraction from doubly curved crystals. In our MMXRF setup, a small x-ray source was produced by the bombardment of a selected target with a focused electron beam and a toroidal mica diffractor with Johann pointfocusing geometry was used to focus characteristic x-rays from the source. In the previous work ∼ 108 photons/s were obtained in a Cu Kα probe of 75 μm × 43 μm in the specimen plane using the fifth order reflection of the (002) planes of mica.

Incorporation and Role of Nitrogen During Oxynitridation of Silicon Studied by Photoelectron Spectroscopy

1999 ◽  
Vol 567 ◽  
Author(s):  
Masayuki Suzuki ◽  
Yoji Saito
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Vacuum ◽  
Oxide Films ◽  
Silicon Surfaces ◽  
Gaseous Mixtures ◽  
X Ray ◽  
Initial Stage ◽  
Thermal Stability Of

ABSTRACTWe tried direct oxynitridation of silicon surfaces by remote-plasma-exited nitrogen and oxygen gaseous mixtures at 700°C in a high vacuum. The oxynitrided surfaces were investigated with in-situ X-ray photoelectron spectroscopy. With increase of the oxynitridation time, the surface density of nitrogen gradually increases, but that of oxygen shows nearly saturation behavior after the rapid increase in the initial stage. We also annealed the grown oxynitride and oxide films to investigate the role of the contained nitrogen. The desorption rate of oxygen from the oxynitride films is much less than that from oxide films. We confirmed that nitrogen stabilizes the thermal stability of these oxynitride films.

scholarly journals Laser power meters as an X-ray power diagnostic for LCLS-II

2018 ◽  
Vol 25 (1) ◽  
pp. 72-76 ◽  
Author(s):  
Philip Heimann ◽  
Stefan Moeller ◽  
Sergio Carbajo ◽  
Sanghoon Song ◽  
Georgi Dakovski ◽  
...  
Keyword(s):  
Free Electron Laser ◽  
Laser Power ◽  
High Vacuum ◽  
Average Power ◽  
Gas Analysis ◽  
Ultra High Vacuum ◽  
Beam Path ◽  
X Ray ◽  
High Repetition ◽  
Residual Gas

For the LCLS-II X-ray instruments, laser power meters are being developed as compact X-ray power diagnostics to operate at soft and tender X-ray photon energies. These diagnostics can be installed at various locations along an X-ray free-electron laser (FEL) beamline in order to monitor the transmission of X-ray optics along the beam path. In addition, the power meters will be used to determine the absolute X-ray power at the endstations. Here, thermopile power meters, which measure average power, and have been chosen primarily for their compatibility with the high repetition rates at LCLS-II, are evaluated. A number of characteristics in the soft X-ray range are presented including linearity, calibrations conducted with a photodiode and a gas monitor detector as well as ultra-high-vacuum compatibility tests using residual gas analysis. The application of these power meters for LCLS-II and other X-ray FEL sources is discussed.

scholarly journals The time-resolved hard X-ray diffraction endstation KMC-3 XPP at BESSY II

2021 ◽  
Vol 28 (3) ◽  
Author(s):  
Matthias Rössle ◽  
Wolfram Leitenberger ◽  
Matthias Reinhardt ◽  
Azize Koç ◽  
Jan Pudell ◽  
...  
Keyword(s):  
Storage Ring ◽  
Single Photon ◽  
Laser System ◽  
High Vacuum ◽  
Laser Pulses ◽  
Pixel Detector ◽  
X Ray Diffraction ◽  
Optical Pump ◽  
Time Resolved ◽  
X Ray

The time-resolved hard X-ray diffraction endstation KMC-3 XPP for optical pump/X-ray probe experiments at the electron storage ring BESSY II is dedicated to investigating the structural response of thin film samples and heterostructures after their excitation with ultrashort laser pulses and/or electric field pulses. It enables experiments with access to symmetric and asymmetric Bragg reflections via a four-circle diffractometer and it is possible to keep the sample in high vacuum and vary the sample temperature between ∼15 K and 350 K. The femtosecond laser system permanently installed at the beamline allows for optical excitation of the sample at 1028 nm. A non-linear optical setup enables the sample excitation also at 514 nm and 343 nm. A time-resolution of 17 ps is achieved with the `low-α' operation mode of the storage ring and an electronic variation of the delay between optical pump and hard X-ray probe pulse conveniently accesses picosecond to microsecond timescales. Direct time-resolved detection of the diffracted hard X-ray synchrotron pulses use a gated area pixel detector or a fast point detector in single photon counting mode. The range of experiments that are reliably conducted at the endstation and that detect structural dynamics of samples excited by laser pulses or electric fields are presented.

scholarly journals Fortification of Rice Grain with Gac Aril (Momordica Conchinchinensis) Using Vacuum Impregnation Technique

2018 ◽  
Vol 6 (2) ◽  
pp. 412-424
Author(s):  
Eko Hari Purnomo ◽  
Fransiska Agatha Nindyautami ◽  
Nattaya Konsue ◽  
Pattavara l Pathomrungsiyounggu
Keyword(s):  
Antioxidant Activity ◽  
Pulse Pressure ◽  
Rice Variety ◽  
High Vacuum ◽  
Vacuum Pressure ◽  
Vacuum Impregnation ◽  
Total Phenolic ◽  
Rice Grain ◽  
Β Carotene ◽  
Unpolished Rice

The objective of this research was to improve functional property of rice by fortification with gac aril using vacuum impregnation (VI) process. Effects of rice variety, preparation method and VI condition on gac aril fortified rice quality were investigated. Sao Hai (SH) and Khaw Dok Mali 105 (KDML 105) were prepared to achieve polished and unpolished rice. The samples were impregnated with 30% gac aril solution under VI condition (vacuum pressure 500 mmHg), 0% gac solution was used as a control. After drying, the samples were analyzed for physicochemical property i.e. texture, color L*, a* and b*, total fiber, lycopene, β-carotene and total phenolic (TPC) content and antioxidant activity (DPPH assay) as well as sensory quality (9-point hedonic scale). The results showed that both varieties of unpolished rice had higher hardness and darker colour than polished samples. Unpolished SH impregnated with gac aril showed the highest content of β-carotene (22.10±0.83 mg/g), lycopene (8.38±0.11 µg/g), and TPC (0.24±0.03 mg GAE/g) while antioxidant activity of all gac aril fortified samples were not significantly different (p>0.05) (DPPH value ranged 1.39-1.72 mmol TE/ g) and higher than control. However, sensory evaluation showed that gac fortified unpolished KDML 105 had the highest score of the overall acceptability. Based on all properties, unpolished KDML 105 was chosen for studying the suitable VI condition in further step. Unpolished KDML 105 was soaked in 30% gac aril solution under different vacuum pressures (0, 300 and 500 mmHg) and pressurizing techniques (single and pulse pressure). The dried samples were analyzed and it was found that the high vacuum pressure at 500 mmHg and pulse pressure gave the highest β-carotene (41.41 ± 4.53 mg/g), lycopene (25.07 ±1.74 µg/g) and TPC (0.21±0.03 mg GAE/g) content and DPPH value (2.91±0.90 mmol TE/ g), while physical properties, texture and sensory were not significantly different (p>95%). In addition, glycemic index (GI) of rice after VI process was decreased from 84.24 to 72.04. Finally, it can be concluded that non-polishing process, high vacuum pressure and pulse pressurizing are the suitable condition to prepare gac aril fortified rice. The health benefits of rice are improved with high antioxidant activity and lower GI.

New Rotating Anode X-Ray Generator For XAFS Experiments

1995 ◽  
Vol 39 ◽  
pp. 149-153
Author(s):  
Kenji Sakurai
Keyword(s):  
High Vacuum ◽  
Lanthanum Hexaboride ◽  
X Rays ◽  
Tube Voltage ◽  
X Ray ◽  
Low Tube Voltage ◽  
Tube Current ◽  
Sample Position ◽  
Good Energy ◽  
X Ray Absorption

A high-power X-ray generator equipped with a lanthanum hexaboride cathode has been developed for X-ray absorption fine structure experiments. A high tube-current of more than 1,000 mA can be provided when operated at low tube-voltage of less than 20 kV. In addition, the focal width is narrow enough (less than 0.1 mm) to ensure good energy resolution. Extremely intense monochromatic X-rays (106 ∼ 107 counts/(sec.mm2) at the sample position), which are completely free from higher order harmonics and tungsten contamination lines, are available, when a Johansson-type spectrometer is employed. The filament life has been significantly prolonged by the high vacuum specification of the tube.

Evaluation of Corrections for X-Ray Microanalysis in the ESEM

2001 ◽  
Vol 7 (S2) ◽  
pp. 698-699
Author(s):  
Robert A. Carlton ◽  
Charles E. Lyman ◽  
James E. Roberts ◽  
Raynald Gauvin
Keyword(s):  
Electron Beam ◽  
Vapor Pressure ◽  
Path Length ◽  
High Vacuum ◽  
Chamber Pressure ◽  
Environmental Scanning ◽  
X Ray ◽  
Scattering Effects ◽  
Beam Scattering ◽  
The Relationship

A number of methods have been proposed to correct for the electron beam scattering effects on xray microanalysis in the environmental scanning electron microscope (ESEM). This paper presents an evaluation of two of these methods. The Doehne method is based on the observation that x-ray counts due to the unscattered electron beam increase with decreasing chamber pressure whereas the inverse is true for x-ray counts due to scattered electrons. The x-ray count intercept, at zero pressure, of the regression lines relating x-ray counts to chamber vapor pressure is an estimate of the high-vacuum intensity. The Gauvin method is based on the relationship between x-ray counts and the fraction of the electron beam that is unscattered, fp.The fraction of the unscattered beam is calculated using an equation derived from scattering theory and uses the accelerating voltage, the gas path length, and the chamber vapor pressure.

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