EFFICIENCY AND EVALUATION - Total-Reflection X-Ray Fluorescence Analysis and Related Methods - page 414

Total reflection XRF instrumentation exists on six continents and in more
than 50 countries at about 200 institutes and laboratories. The number of
running spectrometers applied for TXRF and related methods amounts to
nearly 300. Most of them are desktop instruments. Forty-three percent are
localized in Europe, 23% in Asia, 16% in North and Central America, and 11%
in South America. Countries with a high percentage are Germany with 17%,
USA with 9%, and Japan with 6%. Most instruments were produced by the five
companies enumerated in Section 6.3.1.
Several small and developing countries also have such devices, mostly low-
priced attachment modules. Nearly 50 ATI instruments were distributed with
the help of the IAEA to countries, such as Costa Rica, Guatemala, and Panama
in Central America; the Dominican Republic and Jamaica in the Caribbean;
Mongolia and Singapore in Asia; and Bolivia, Paraguay, and Uruguay in South
America. A very few instruments are home-made.
Figure 6.11 shows the distribution of today's running TXRF equipment in a
world map with six continents. The Robinson projection depicts the whole
globe as a flat image with a good area and angular conformity aside from severe
distortions near the poles. Figure 6.11a represents TXRF equipment of the first
group of users (universities and scientific institutes) as red bars in 51 different
countries. Figure 6.11b depicts an accumulation of TXRF instruments in 24
subregions, largely delineated after the United Nations. All data are minimum
values and give a picture of TXRF's distribution, which is fairly realistic though
not absolutely exact.
In addition to the first group of TXRF users, a second group is considered
working at several synchrotron beamlines at a work place exclusively dedicated
to TXRF and related methods. Instead of a separate X-ray tube, they can use
the synchrotron beam for excitation preferably with a monochromator. In
addition, a six-axis sample stage and an energy-dispersive detector are neces-
sary. Unfortunately, precise numbers of all particular working stations for
TXRF in the different subregions are not available. For 2014, the authors of this
book estimate their total number at about 55 stations in 25 countries. Several
beamlines have even two or three work places used for TXRF applications.
They are represented in Figure 6.11b as blue bars in 15 subregions. Recently, a
new work station was established at the Shanghai Synchrotron Radiation
Facility (SSRF), dedicated to XANES and XRR measurements at grazing
incidence [109]. In a first study, Ti/Ni/Ti layers were investigated with different
nm-thick central Ni layers and interfacial diffusion could be observed.
The third group of TXRF users is represented by chemical laboratories in
industry, especially in the semiconductor industry with particular interest in
wafer control. Some figures illustrate the use of TXRF in the wafer indus-
try [110]: in 2013 more than 25 companies with more than 150 semiconductor
fabrication plants—known as fabs—produced and supplied silicon wafers
worldwide. They are distributed in more than 15 countries. The United States
with 36% leads the group (23% are concentrated in six states alone: AZ, ME,
MN, NY, OR, and TX). It is followed by Taiwan with 19%, China with 8%, and