Now, researchers at the University of Illinois have demonstrated a method for simultaneous structural and chemical characterization of samples at the femtogram level (a femtogram is one quadrillionth of a gram) and below.
The measurement technique combines the extraordinary resolution of atomic force microscopy and the excellent chemical identification of infrared spectroscopy.
“We demonstrated that imaging, extraction and chemical analysis of femtogram samples can be achieved using a heated cantilever probe in an atomic force microscope,” said William P. King, a Kritzer Faculty Scholar and professor of mechanical science and engineering.
King and colleagues describe the technique in a paper accepted for publication in the journal Analytical Chemistry, and posted on its Web site.
The new technique hinges upon a special silicon cantilever probe with an integrated heater-thermometer. The cantilever tip temperature can be precisely controlled over a temperature range of 25 to 1,000 degrees Celsius.
Using the cantilever probe, researchers can selectively image and extract a very small sample of the material to be analyzed. The mass of the sample can be determined by a cantilever resonance technique.
To analyze the sample, the heater temperature is raised to slightly above the melting point of the sample material. The material is then analyzed by complementary Raman or Fourier transform infrared spectroscopic imaging, which provides a molecular characterization of samples down to femtogram level in minutes.
“Fourier transform infrared and Raman spectroscopic imaging have become commonplace in the last five to ten years,” said Rohit Bhargava, a professor of bioengineering. “Our method combines atomic force microscopy with spectroscopic imaging to provide data that can be rapidly used for spectral analyses for exceptionally small sample sizes.”
To clean the tip for reuse, the tip is heated to well above the decomposition temperature of the sample – a technique similar to that used in self-cleaning ovens.
“Since the tip can be heated to 1,000 degrees Celsius, most organic materials can be readily vaporized and removed in this manner,” King said.
As a demonstration of the technique, the researchers scanned a piece of paraffin with their probe, and removed a sample for analysis. They then used Raman and Fourier transform infrared spectroscopy to chemically analyze the sample. After analysis, the paraffin was removed by thermal decomposition, allowing reuse of the probe.
“We anticipate this approach will help bridge the gap between nanoscale structural analysis and conventional molecular spectroscopy,” King said, “and in a manner widely useful to most analytical laboratories.”
With King and Bhargava, co-authors of the paper are postdoctoral researcher and lead author Keunhan Park and postdoctoral research associate Jung Chul Lee. All four researchers are affiliated with the university’s Beckman Institute.
The work was funded by the National Science Foundation through the Center for Nanoscale Chemical-Electrical-Mechanical Manufacturing Systems, and by the U. of I.
James E. Kloeppel | University of Illinois
Physics boosts artificial intelligence methods
19.10.2017 | California Institute of Technology
NASA team finds noxious ice cloud on saturn's moon titan
19.10.2017 | NASA/Goddard Space Flight Center
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
19.10.2017 | Materials Sciences
19.10.2017 | Materials Sciences
19.10.2017 | Physics and Astronomy