Gold used for non-destructive chemical analyses of mostly rocks

Gold is one of
the valuable metals based on emitting light, reflecting energy, and resisting obscuration.
Physical Vapor Deposition (PVD) Gold Sputtering is widely used in the production
of watch and jewelry that won’t wipe off or lose brightness when having contact
with your skin and clothes. Also, it is used to coat circuit panels and
electronic components thanks to its excellent conductivity.Figure 1. Sample of PVD Gold SputteringX-ray powder
diffraction (XRD) determines the phase of a crystalline material and unit cell
dimensions. Energy-dispersive
x-ray spectroscopy (EDS) distinguishes the characteristic x-rays of each elements
into an energy spectrum and determines the chemical composition of materials. Its
software analyzes the energy spectrum to determine the number of specific
elements. EDS systems are integrated into SEM instrument.X-ray
fluorescence (XRF) spectrometer is used for non-destructive chemical analyses of
 mostly rocks and minerals. In our cases,
analyzed material is sputtered gold.1.   
Materials and MethodsIn PVD Gold
Sputtering process, gold is bombarded with high energy ions in a vacuum chamber
in order to the gold atoms or molecules are sputtered into the vapor and
condense on the substrate coating. Basically, the function
of a diffractometer is detecting X-rays from materials and recording the change
of diffraction intensity with the diffraction angle (2?). As is seen from Figure
2, the X-ray source, specimen and detector are geometrically arranged. The
X-ray tube creates X-ray radiations which passes through special slits to align
the X-ray beam. The divergent X-ray beams hit the specimen. In general, the sample
flat plate shaped. Finally, diffracted X-rays by the specimen in the form a
convergent beam at receiving slits enters a detector 1.Figure 2. Geometric arrangement of X-Ray
diffractometer 1. A scanning
electron microscope (SEM) composes of an electron gun and a set of
electromagnetic lenses and apertures as indicated in Figure 3. An SEM optical
path passes through several electromagnetic lenses which comprise condenser lenses
and an objective lens. The apertures are used to collimate the divergence of
the electron beam in its optical path 1.  Figure 3. Structure of a scanning electron
microscope (SEM). (Reproduced with kind permission of Springer Science and
Business Media from J.I. Goldstein et al, Scanning ElectronMicroscopy and X-ray
Microanalysis, 2nd ed., Plenum Press, New York. © 1992 Springer Science.)Commonly, EDS
type of X-ray spectrometer is assembled in SEM. The EDS instrument uses a
photon detector, generally a Si(Li) diode, to disperse the characteristic X-ray
photons in compliance with their energies as shown in Figure 4 1.Figure 4. Main components and dispersive spectra
of EDS 1. 

X-ray
fluorescence spectrometry (XRF) is used to analyze the chemical elements of samples
by detected the characteristic X-rays emitted from the samples. If the
characteristic X-rays is analyzed from their energies, it would become energy
dispersive spectroscopy (EDS). The X-ray source, detection system, and data
collection and processing system are three basic parts of an XRF instrument. The
primary X-rays to excite atoms of samples are created the X-ray source. The
X-ray tube is operated with high voltage of 30–50 kV due to ensure that the
X-rays impinging the sample exceed the critical potential of exciting
characteristic X-rays from the elements in samples. The X-ray radiation is generated
by electrons hitting a metal target in the tube that metals contain Cr, Rh, W,
Ag, Au and Mo 1.

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