Spectrometer, ESCA

The sanples were subjected to reduction treatment with in the reaction chamber directly attached to the ESCA spectrometer. 

The 5950A ESCA spectrometer is interfaced to a desktop computer for data collection and analysis. Six hundred watt monochromatic A1 Ka X-rays are used to excite the photoelectrons and an electron gun set at 2 eV and 0.3 mAmp is used to reduce sample charging. Peak areas are numerically integrated and then divided by the theoretical photoionization cross-sections (11) to obtain relative atomic compositions. For the supported catalyst samples, all binding energies (BE) are referenced to the A1 2p peak at 75.0 eV, the Si 2p peak at 103.0 eV, or the Ti 2p3/2 peak at 458.5 eV. 

A Hitachi EPI-S2 infrared spectrometer, a contact angle meter (Kyowa Kagaku Co. Type CA-P) and an ESCA spectrometer(Kokusai Den-ki Co.) were used for relevant measurements. 

Detailed analysis of the chemical shifts demands higher resolution than a basic ESCA spectrometer can provide. The needed resolution improvement may be achieved experimentally by monochromatizing the x rays and/or by high-resolution energy analysis of the electrons. Either way, because of the reduced slit widths required, penalties are paid in decreased signal-to-noise ratio and longer observation time. Furthermore, the problem of sample charging (Section IV.D) is typically more severe when monochromatized x rays are used (Brundle and Baker, 1981). 

All XPS or ESCA measurements were performed using a Perkin Elmer 5300 ESCA spectrometer equipped with a dual anode (Mg, Al) X-ray source, differentially pumped Ar+ sputter gun, and the variable angle measurement set-up for angle-resolved photoelectron spectroscopic measurements. The data collection and treatment, e.g. smoothing, curve-fitting, intensity measurements, were accomplished by a Perkin Elmer 7500 dedicated computer system using PHI software package. 

The ESCA spectrum was obtained by Dr. Grunthaner on HP 7950A ESCA spectrometer at Jet Propulsion Labs in Pasadena, CA. 

Schematic diagram for an ESCA spectrometer with a specimen transfer within a closed system via a purified argon atmosphere between an electrochemical cell and the UHV with three chambers and an attached electrochemical chamber [v, vi]...

Figure 2. Diagram of an ESCA spectrometer. Key X, X-rays A, sample B, electron analyzer C, detector D, amplifier E, computer F, recorder.

XPS has been used, in quite a different context from its usual application in metal systems, by Defosse and Canesson " they studied the acidity of catalysts important in cracking, isomerization, and dehydration. They used a NH4-Y zeolite, prepared from Na-Y. Samples were activated by being heated in vacuum at temperatures between 20 and 900 °C. Pyridine was admitted to the samples at 20 °C and samples were transferred direct to the ESCA spectrometer. 

Spectroscopy. Transmission and ATR IR spectra were obtained with a Perkin-Elmer Model 180 or 621 spectrometer. Absorption spectra were obtained on a Cary 14 spectrophotometer, while ESR spectra were obtained with a Varlan V-4502 spectrometer in the manner described elsewhere ( ). X-ray photoelectron spectra of the etched and unetched films were provided by Surface Science Laboratories, Palo Alto, Calif., using a Hewlett-Packard Model 5950 ESCA spectrometer. Some films were also examined with an International Scientific Instruments Model MSM-2 "Minl-Sem" scanning electron microscope. 

Knowledge of the work function and Fermi (reference) level of the spectrometer is important if one wishes to obtain meaningful absolute E, values. The ESCA spectrometer should be periodically checked by measuring the energy of photoelectrons emitted from a sample with a well-established E > (e.g. the Au4f7/2 level at 83.96 eV). 

X-ray photoelectron spectroscopy (XPS). These studies were performed at the Amoco research center at Naperville, Illinois, by Dr. Theo Fleisch. A Hewlett Packard 5950B ESCA spectrometer was employed using a monochromated A1 source. Sample wafers were pressed from approximately 50 mg of catalyst powder, and placed in a pretreatment chamber attached to the spectrometer. 

XPS measurements were performed in a MARK-II ESCA spectrometer with a pretreatment cell without exposure to the air. Hydrogen reduction of the sample was carried out at 723 K in the pretreatment cell. Binding energy measuremensts were related to the C[ls) photoelectron line at 285.0 eV as a reference. Structural analysis of the zeolite samples was completed In a Shlmadzu XD-3A diffractometer. 

The state of Pt in MCM-41 catalysts prepared by ion-exchange, in-situ synthesis and impregnation evaporation was investigated by XPS (Perkin-Elmer 5400 ESCA spectrometer). 

Instrumental Methods. A Hewlett-Packard 595B ESCA spectrometer was utilized in the ESCA studies of the block copolyether-urethane-urea and model polymer films. The samples were allowed to come to equilibrium at 10-9 Torr at 300... 

The surface of an aluminum sample was thoroughly cleaned by abrasion and immediately put into the sample chamber of an ESCA spectrometer. Two prominent peaks in the spectrum occurred at binding energies of 72.3 and 75.0 eV, whose relative intensities were 15.2 and 5.1 (arbitrary) units. After a week s exposure to laboratory air, the same sample was rerun under the same conditions the two peaks were again ob-... 

The elemental compositions of modified PU surfaces were determined by using a Physical Electronic PHI 558 electron spectroscopy for chemical analysis (ESCA) spectrometer. The source was a 10 kV, 30 mA monochromatized X-ray beam from a magnesium anode. Surface charge build-up was corrected by considering the shift of peak at 285 eV. 

The XPS measurements were performed using the Hewlett-Packard 5950B ESCA Spectrometer System. The procedures used are outlined elsewhere (1 2). 

The samples were characterized by routine examination with a Hewlett Packard ESCA Spectrometer, Model 5950A. After analysis, the samples were withdrawn and placed immediately in a humidity chamber at 60 C, 100% R.H. After one hour they were removed, air dried, and re-examined. Surface water was removed during evacuation in the sample chamber. 

Schematic of magnetic and electrostatic analyzers used In ESCA spectrometers.

Fig. 10.99. Schematic diagram of an ESCA spectrometer [1823]. (Reproduced with permission from Ratner, B.D., in Polymers in Medicine II (eds Chiellini, E. et al) published by Plenum Press, NY, 1986.)...

X-ray Photoelectron Spectroscopy examination was used to determine the fimctional groups on the surface of the cured matrix. A Perkin Elmer Physical Electronics PHI 5400 ESCA spectrometer equipped with standard magnesium x-ray source operated at 300 W (15 kV and 20 mA) was used for surface analysis. 

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