With the JSM-6610, JEOL’s small and medium-sized customers found, many for the first
time, that they could afford to have an in-house
SEM with EDS capability. The IT300LV represents
the next level up, improving resolution performance to 3 nm at 30 kV and a magnification
range of 5 to 300,000X. Like the previous 6610
Series, the vacuum chamber is large to accommodate a wide variety of large and heavy samples.
But elsewhere the new LV-SEM differs from
the 6610 Series more dramatically. A major
design change was precipitated by the increasing
utility of spectroscopy, particularly EDS x-ray
microanalysis. These instruments provide chemical information about the sample, which can be
constructively paired with the structural resolving power of the electron beam.
“For years, people have done EDS analyses
in conjunction with SEM. Typically, they would
attach one spectrometer, and that spectrometer
was quite small,” says Robertson. “They would
struggle to get x-ray counts.”
Two things have changed in recent years,
however. One, users have added multiple types of
imaging detectors and spectroscopy on the tung-
sten microscopes. Two, the EDS manufacturers
started making larger, higher sensitivity detec-
tors, increasing from 10 mm2 for EDS to greater
than 100 mm2 today.
“The acquisition rate is either 10-fold faster
for the same amount of data, or 10 times the
data for the same acquisition time, improving
both data quality and throughput,” says Robertson.
One solution is to increase the number of
attachment points for imaging and spectrometry, which JEOL has done for the IT300LV. The
instrument has multiple ports for EDS, electron
backscatter diffraction, cathodoluminescence
detectors, wavelength dispersive x-ray spectrometers, chamberscopes or heating/cooling
But this wasn’t the only change during the
redesign of the chamber. A major limitation of
x-ray spectroscopy is its line-of-sight; because
x-rays don’t have a mass or charge, they can’t
usefully resolve highly textured surfaces and
produce significant shadowing. In recognition
of this effect, JEOL’s engineers revised the chamber design so EDS detectors could be placed
180 degrees apart from each other. This has the
effect, says Robertson, “of removing the topogra-
phy on less than ‘ideal’ samples, which comprise
most of the real-world samples.”
Another change for the IT300LV, and one that
may appeal most to the traditional microscopist,
is the 650-Pa pressure range, which is more than
twice that of preceding models.
According to Robertson, the audience for
this type of low-pressure microscope is niche
relative to general analytical SEMs; but the level
of interest in analyzing wet samples, oily samples and samples of unusual size or shape, will
continue to grow. Strong growth in areas such
as food and plant analysis, petroleum or bio-fuels studies and biofilms has prompted JEOL
to make an effort to improve the pressure range.
The design change allowing increased pressure
has been to reroute the pumping mechanism
through electron optics infrastructure. This
allows extra pumping to prevent gas from migrat-
ing up the column where the gun is located.
“This helps elevate the pressure, and it’s the
first design we’ve done in that regime,” says
Robertson. Other vendors have adopted a sim-
ilar design for certain instruments, and this is
still typically focused on a small, niche market.
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