iCAP Q ICP-MS system. The first major change from prior systems is the QCell ion collision cell. High- sensitivity ICP-MS operations require ion guides to suppress interferences, and these are typically quad- rupoles that offer a well-defined stability boundary to cut off lower masses before they react further down the cell. The rectangular-shaped “flatapole” does the same job, but in a smaller cell volume. In addition to a new ionization cell, substantial revisions to the optics package reduced the number
of lenses required. In addition to these measures
to achieve a cleaner ion beam for more sensitive
results, Thermo Fisher Scientific’s engineers rerouted the ion beam to
allow a substantial change in the typical ICP-MS architecture, which is
often a long, low instrument that consumes a lot of bench space.
“We’ve achieved a 90-degree reflection of the ion beams, which allows
the remainder of the analyzer to be configured in a vertical orientation. This has reduced the lab bench in use by a substantial amount, and
researchers can put a high premium on this characteristic,” says Lothar
Rottmann, Product Mgr. for ICP-MS at Thermo Fisher Scientific.
The iCAP Q can be used with ion chromatography to establish a highly
selective speciation workflow in a relatively small area of bench space.
but it would produce tens of thousands of data points.
As algorithms developed, survey scanning became
possible. This has become important in certain types
of studies such as those for graphene and molybde-
num sulfide. Traditionally, triple spectrometers have
been used for these studies, but the volume Bragg
grating filters used on these instruments, though
they can detect down to five wave numbers from
the baseline, lack speed. For detecting mechanical
characteristics such as shear stress, they are not
Horiba’s XploRA ONE is being used increasing-
ly for this type of study. Designed as a mid-range single Raman spectrom-
eter, the XploRA incorporates a high-optical-throughput imaging system
that features a fast detector stage that allows millisecond Raman mapping.
The system was designed specifically to allow mapping capability on a con-
focal-grade microscopy system. This capability, says Whitley, is important
for small particles and thin layers. Algorithms can show layer thickness
and how many layers are at a given point. Low frequency measurement can
show shear mode, which is measured at high frequency and throughput.
The popularity of Raman has been aided by the appearance of smaller
instrumentation packages. Whitley says the future of Raman technology
will inevitably involve various types of MEMS technology, particularly for
fast, mobile applications such as environmental research and geochemistry. The popularity of handheld x-ray fluorescence (XRF) spectrometers
for field use is one example. Modern guide tubes used in these XRF instruments measure just 10 um.
One of the constraints faced by spectrometer developers is the need for
vacuum to eliminate soft radiation and increase sensitivity. Horiba’s MESA
50, for example, is a lunchbox-sized x-ray fluorescence spectrometer that is
more capable than the handhelds. Horiba worked to reduce its size by five
times from the previous model.
Whitley says, however, that double and triple spectrometers, despite
their cost and complexity, will always have a prominent place in scientific
research. On the back end of a renewed interest in Raman techniques,
Horiba continues to update its comprehensive Raman platforms, such
as the T64000. This instrument incorporates Horiba’s confocal LabRAM
Raman microprobe, which features a stable mechanical coupling and an
efficient optical coupling. It can be used to apply ultraviolet, resonance
Raman, plasmonics and laser fluorescence. Its holographic notch filter
technology allows the acquisition of spectral data close to the laserline,
where stray light drastically reduces signal intensity. A “double subtractive”
monochromator, which acts like a bandpass to eliminate unwanted wavelengths, gives the spectrometer no temporal dispersion, allowing researchers to closely study semiconductor materials.
Thermo Scientific iCAP Q. Image: Thermo
Fisher Scientific Inc.
The revitalization of Raman
Another example of how new technologies can transform well-established spectroscopy methods is Raman imaging. After languishing behind
methods such as FTIR, Raman is increasingly looked to by researchers.
The catalyst, says Whitley, whose company is the largest vendor of Raman
spectrometers, is the advent of charge-coupled devices (CCDs).
Whitley first encountered Raman spectroscopy while earning his doctorate for spectroscopic studies of lubricants. The emergence of CCDs was
important because they are extremely sensitive to light. The elements in
the detector interact with light to build charge, offsetting a Raman signal
that is inherently weak. The other equally important contribution is the
possibility of multichannel operation, which can acquire the entire Raman
The next advance was the introduction of notch filters, which are
designed to reject a pre-selected wavelength band or region while transmitting all other wavelengths within the design range of the filter. This
improved on beamsplitters because it reduced signal loss. This produced
a big improvement in sensitivity, says Whitley, and offered a new way to
conduct spectroscopy studies. By pairing the filter-equipped and CCD-equipped spectrometer with a microscope, researchers could then conduct
rapid scanning studies to determine areas of interest, or even to simply
reject a sample without spending too much time studying it.
This process, called “mapping”, was a major advance in throughput that
required a major shift in thinking about how to conduct a Raman study,
says Whitley. Specificity and signal-to-noise ratios were still important, but
they weren’t necessarily crucial to every study. Instead the emphasis shifted
“People didn’t immediately think to go fast. They were used to needing 0.1 sec for a data point,” says Whitley. That data point represented high
quality. But with scanning, a lower resolution didn’t matter as much as the
vast amount of data compiled. If using a CCD, says Whitley, 1 msec per data
point became possible. When mapping, this could require 5 msec per point,
Where to next?
At Thermo Fisher Scientific, Davies sees data and miniaturization as two of
the big challenges for the development of all types of spectrometers.
For Whitley, one of the biggest hurdles for future advancements in Raman
is the sampling arrangement. The process of taking a sample from Raman
and bringing it to AFM is an important one, he says, but more work needs to