Fast Acquisition

Mon, 08/05/2013 - 1:59pm
Paul Livingstone

Innovations in spectroscopy are allowing some of the most crucial discoveries in science. Instrument vendors are helping make them possible with advances in theory and design.

Horiba Scientific’s LabRAM HR Evolution. Image: Horiba ScientificEarlier this year, physicists working at CERN, the European Organization for Nuclear Research, determined the ionization potential for astatine, a naturally occurring element so rare that, until now, its ionization potential couldn’t be determined. All told, less than a tenth of a gram exists on Earth, which led researchers to create artificial astatine in the laboratory, then test it later using laser spectroscopy.

At Brookhaven National Laboratory’s National Synchrotron Light Source, Upton, N.Y., researchers used x-ray spectroscopy to measure the electronic behavior of a germanium-based transistor design that could allow future transistors to become much smaller.

And at NIST, scientists redesigned the electro-optic components of a spectrometer to allow them to test a wide range of frequencies in a gas sample in just milliseconds. They hope to soon rapidly test greenhouse gas levels on a large scale.

All of this research culminated in recently published work, representing a tiny sliver of the research conducted using spectrometric technologies and instrumentation. Any research requiring greater knowledge of chemical properties or structure will rely on the application of spectrometry techniques.

But not all research requires a synchrotron or a custom-made spectrometer. Laboratory researchers and technicians require high-performance, cost-effective spectroscopy solutions capable of both sensitivity and speed. Because of spectroscopy’s inherent sensitivity and remarkable versatility, demand for cost-effective but potent instrument solutions is growing strongly on a global basis.

For this reason, instrument vendors are compelled to take a leading role in delivering innovations that help boost performance and answer R&D questions.

A growing, domestic technology
The spectroscopy market, which has traditionally been dominated by the U.S. market, is poisted to grow quickly. Reports vary, but on average the growth rate is about 7% per year. In 2011, the market was about $10 billion, and could be $15 billion by 2017.

According to Andrew Whitley, VP of sales for Horiba Scientific, Edison, N.J., the market for advanced spectroscopic equipment has accelerated in the last six months.

“Industry reports are a little off in some of the numbers they quote, but overall the outlook for spectroscopy is good. Raman is very healthy. It’s a fast-growing area,” says Whitley. Sequestration scared some buyers, but the attitude has changed. “Some areas have died down because of cuts in spending and stagnant university demand. But in the last two years, the economy has picked up again. After the government funding tapered off, business has sort of taken over and has been doing fairly well.”

Adrian Holley, Dir. of Marketing for Trace Elemental Analysis at Thermo Fisher Scientific, Waltham, Mass., points to 2009 as a tough recession year for the spectroscopy market. But positive changes in the pharmaceutical markets, particularly with regard to R&D investments, have generated strong demand for instrumentation. Part of the reason, says Holley, is the onset of more stringent regulations.

“There is a drive for more legislation on health-related markets. The push has opened up new elemental chapters. The need for low detection and more detection, as well as the need for our customers to comply with widening regulations, means that demand is strong,” says Holley.

Brian Davies, VP for marketing and product development at Thermo Fisher Scientific, also sees strong growth in materials science.

“We’ve had stellar market growth for molecular spectroscopy products, such as the IS50. We’ve seen an explosion of interest in the analysis of new materials,” he says, which he ties directly to demand. The IS50 is one of Thermo Fisher Scientific’s key Fourier transform infrared (FTIR) instruments. “Customers need us to be able to look at smaller samples and the boundaries between them. FTIR is particularly strong in that area.”

Innovations in the marketplace
Many of these spectroscopy innovations appear in R&D Magazine’s R&D 100 Awards. For example, the 2013 Awards included the 8800 from Agilent Technologies, Japan, the first ICP-MS on the market with a tandem, or MS/MS configuration. The addition of a quadrupole before and after the collision cell allows the 8800 to precisely control ion travel, improving sensitivity. P&P Optica’s PPO SWIR (short-wave infrared) spectrometer is geared for industrial tasks—like process control and mining—and its system design and gel gratings elevate signal-to-noise to 16000:1.

Thermo Scientific iCAP Q. Image: Thermo Fisher Scientific Inc.Inductively coupled plasma mass spectrometry (ICP-MS) is a prime example of the changing spectrometry landscape. ICP-MS, which ionizes the sample with plasma prior to detection, has offered a substantial improvement in performance over trace element analysis methods such atomic absorption, particularly in tasks that require detection of metals. But ICP-MS systems have been bulky, expensive and prone to interference from trace contaminants. In recent years, the bar has been raised considerably; and several major companies, including Bruker, PerkinElmer and Agilent, produce high-quality ICP-MS systems.

Thermo Fisher Scientific received an R&D 100 Award in 2013 for several innovations that have improved the usability and performance of its new 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 quadrupoles 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.

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 spectrum simultaneously.

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 to throughput.

“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, 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 molybdenum 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 suitable.

Horiba’s XploRA ONE is being used increasingly for this type of study. Designed as a mid-range single Raman spectrometer, 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 confocal-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.

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 be done.


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