First and best
A look at two of the spectra generated so far from the C60 SIMS FT-ICR MS – (Top) The first spectrum Don obtained during "The Moment"; (Bottom) An example of a more optimal spectrum the instrument has subsequently generated.
It's sort of a pop-culture cliché: a scientist or scientific team pours heart, soul, and countless hours into a project—nearly to the point of obsession—until The Moment arrives. The first result comes; the instrument works; the data make sense; the code does its job. Whatever the exact fabric of The Moment, it's exactly what the scientist was hoping for—or it's unexpected in an even more interesting way.
While this scene surfaces in the movies, it isn't always how science works in the real world. Often, incremental progress is the norm, and breakthroughs can be more cumulative. However, in the past few months, two EMSL scientists working on separate projects experienced The Moment. Each generated their very first spectra on new, unprecedented scientific instruments they had been developing for months. While they may not have shouted "Eureka," their reactions show the importance of these first results to their respective scientific fields: imaging mass spectrometry and surface nonlinear spectroscopy.
- (High Resolution)2 - Imaging Mass Spectrometry
The Capability: The world's first C60 Secondary Ion Fourier Transform Ion Cyclotron Resonance Mass Spectrometer
The Moment: It was late morning on a regular February weekday. But Dr. Don Smith, analytical chemist and EMSL postdoctoral researcher, began to sense that this would be anything but an ordinary day in the lab. The instrument was telling him he was getting close. He turned a dial or two, making minute voltage adjustments on an experimental tool he had known since it was only a concept. Then: a signal—the world's first mass spectra on this type of instrument. The tool represents a new approach that combines the best of two important experimental worlds: the highest spatial resolution and the highest mass resolution. Smith jumped out of his chair and raised his arms in the air, allowing himself a moment of triumph before immediately grabbing his cell phone and heading outside. He had to call his teammates: Dr. Ron Heeren in Amsterdam, at the Foundation for Fundamental Research on Matter's Institute for Atomic and Molecular Physics; and Dr. Lili Pasa-Tolic, EMSL's mass spectrometry capability lead. After sharing the news, he made a quick personal phone call or two, to savor a once-in-a-lifetime moment with loved ones.
"It was very satisfying," Smith said. "When you work so long toward something that hasn't been done before, it feels great to have it confirmed in the lab that, yes, it is possible, and it will work how we envisioned."
Why it Matters: EMSL's new C60 Secondary Ion Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (SIMS FT-ICR MS) will bring a new dimension to surface analysis—a fundamental science area with broad implications for energy, environmental, and health challenges. This instrument, which was developed in EMSL through the American Recovery and Reinvestment Act, is really two instruments combined.
SIMS is an incredibly useful imaging technique in its own right that is gaining widespread use in analyzing complex materials, both hard and soft. In the usual time-of-flight, or TOF-SIMS, analysis, the sample is bombarded with high-energy (keV) primary ions. In the process, secondary ions are blasted from the surface and mass analyzed. TOF-SIMS is a scanning technique and typically demonstrates spatial resolutions (x-y) of about 250nm. By removing the top layer of molecules one at a time, depth profiling is also possible. Hence, SIMS is a 3-D imaging technique.
But this instrument adds two important features to SIMS analysis, the first being FT-ICR, a tool that provides very high mass accuracy measurements. The high mass accuracy enables distinction of molecules based solely on mass. Second, the high mass resolving power can distinguish peaks which are very closely spaced. This allows scientists to infer the function of the molecule detected at a specific location from the sample (this is also called chemical imaging). In other words, researchers will not only see high resolution images of peptides, proteins, and small molecules—they will know their chemical identities.
"We've been able to make pretty pictures at high resolution for a long time with TOF MS," Heeren said. "Now it is time to move to real applications. But in order to do that, we need to know what the molecules are. So we've integrated the highest spatial resolution resources with the highest mass resolution mass spectrometers available at EMSL. It's high resolution squared—and it's the very first of its kind."
During the effort, Heeren paid extended visits to EMSL as a Wiley Visiting Scientist and worked through a partner proposal to develop this capability with Pasa-Tolic, Smith, EMSL's Instrument Development Laboratory, and EMSL's machine shop.
Telling the world: Smith will present first results from this capability at the 59th Annual American Society of Mass Spectrometry Conference, June 5 - 9, 2011 in Denver, Colorado. "We hope the community is as excited about it as we are," he said.
- Buried Treasure - Surface Nonlinear Spectroscopy
The Capability: New surface nonlinear spectroscopy capability: picosecond-femtosecond broadband sum frequency generation system
The Moment: In Dr. Hongfei Wang's spectroscopy laboratory at the end of EMSL's main hallway, the lights are always off. Because the instrumental capability his team has built uses lasers as its main weapon, light interference would hinder scientific results. So Wang, postdoctoral researcher Dr. Luis Velarde, and visiting scientist Dr. Xianyi Zhang constantly wear headlamps in the lab, giving them the appearance of old-time coal miners. But instead of coal, they are digging up never-before-seen data to reveal molecular interactions at interfaces. This February, they struck a vein that could lead scientists in many fields to research gold.
When the first high resolution vibrational spectrum of the air/DMSO interface appeared on the screen (DMSO is Dimethyl sulfoxide, a very common and important solvent), Wang immediately began to celebrate: after shaking hands with the others and taking a few pictures with his phone, he burst into the hallway to show the evidence to whoever happened to be around. After six months of system design and configuration, and another six months of delivery, installation, and seemingly endless testing, it was finally up and running: the picosecond-femtosecond broadband sum frequency generation system was ready to provide a new generation of surface vibrational spectroscopy and imaging.
Shining New Light on Interfaces: The EMSL team that developed the new nonlinear surface spectroscopy system: (Left to right) Dr. Xianyi Zhang, Dr. Luis Velarde, and Dr. Hongfei Wang."I was very relieved," he said. "We expected it to happen, and it happened. Now we know we have something that is truly unique—the SFG community has been waiting for this, and many scientific fields will benefit."
Back in the lab, Velarde hadn't started celebrating yet. He wanted to make sure everything was just as they expected it would be, and that the spectrum was genuine proof of the system's capability. When he was satisfied, he finally let himself enjoy the moment as well.
For Wang, the milestone was more than a successful project at work; it confirmed his decision to leave his home nation and a job at the Chinese Academy of Sciences in 2009.
"EMSL is the perfect place to develop this capability. Not many places offer an environment like this, and surface chemistry is crucial to all three of EMSL's science themes." He added, "After we generated the first spectrum, I called my wife to tell her: the decision to move here has been validated."
Steeper is better: A look at two spectra generated by the new system, as well as a comparison with previous capabilities. (Left) The first narrow band spectrum achieved during "The Moment" in February 2011; (Middle) A subsequent spectrum with an improved signal-to-noise ratio taken a few days later; (Right) A broader spectrum for comparison, taken with a typical laser source.Why it Matters: Sum frequency generation (SFG) is a highly specialized surface nonlinear spectroscopy technique scientists use to analyze molecular interactions at surfaces and interfaces of all kinds. It is an important, crosscutting technique that can unlock new discoveries in several energy, environmental, and health-related research areas. While the technique has been pioneered by Professor Ron Shen at Berkeley in the 1980s, there is a very small community worldwide that can perform these very difficult experiments to understand the one or few layers of molecules at various interfaces. As for resolution, strength, and efficiency of this capability, this recent "Moment" demonstrates that Wang and his team now stand alone. Previous techniques forced researchers to choose between signal strength and resolution, and carry out time-intensive examinations of each specific data point. The new system in EMSL for the first time synchronises two powerful lasers with completely different characteristics. Namely, one has very short laser pulses (35fs, 1fs=10-15 second) which provides the ultrafast time resolution, and another has very long pulses (100ps, 1ps=10-12 second) which provides the high spectral resolution. This offers the best of both worlds: reliable data is gathered in a few seconds or minutes, at more than ten times the best previously documented spectral resolution with the similar systems. Specifically, they achieved 0.7cm-1 spectral resolution, versus>15cm-1 resolution. With these gains, the tool is ready to reveal detailed molecular conformation and interactions at the molecular interface.
The capability is best shown by example: imagine a team of researchers who want to examine a sample with a liquid-liquid interface: oil and water. This is an example of a "buried interface"—a difficult case for many experimental techniques. SFG specializes in this problem. Experimentalists like Wang interrogate the sample by shooting two pulsed lasers through the oil and water so they meet at the liquid-liquid interface at an exact time (on the picosecond scale). If done correctly, the signal the sample sends back is "surface sensitive"—which means it selects only information about the interface (the two-atom-wide molecular interaction the scientists care about), clearing away the background noise. The resulting spectra allow researchers to piece together what is truly happening on a molecular level—such as how these molecular groups are oriented. In the case of where oil and water meet, deeper fundamental information can provide new insights for environmental cleanup. In addition, the use of lasers causes far less damage to the sample (as opposed to bombarding it with ions) and allows scientists to perform in situ experiments that replicate true environmental conditions.
Telling the World: Wang is often invited to give talks around the world on surface nonlinear spectroscopy. On March 16, 2011, he gave a seminar of his latest findings at Oregon State University in Corvallis, Oregon, and he will do the same at Rice University in October.
Like all of EMSL's experimental and computational tools, the C60 SIMS FT-ICR MS and new surface nonlinear spectroscopy capabilities are available at no cost to the global scientific community through EMSL's user proposal process.
Learn more about EMSL's mass spectrometry and spectroscopy and diffraction capabilities.
Do you have a story of a big scientific "Moment" from your career? Let us know at emslcom@pnl.gov, and we'll include some of your responses in the next Molecular Bond.