‘Big G’ gravitation measurements; hyperspectral infrared nanoimaging.
‘Big G’ gravitation measurements
The National Institute of Standards and Technology (NIST) has unveiled a new coordinate measuring machine (CMM). The CMM, dubbed Xenos, makes measurements that involve “big G” or the universal constant of gravitation.
Basically, there are two meanings for the constant of gravity. The first is Newton’s universal law of gravitation. For this, the speed of an object falls about 32 feet per second near the earth’s surface. This is known as “little g.”
In contrast, “big G” is an empirical physical constant, which involves the gravitational force between two bodies. “Big G” is hard to measure. It is weak compared to other fundamental forces, as its value is a “trillion trillion trillion times” weaker than an electromagnetic force, according to NIST. On top of that, “big G” measurements do not converge on a single value. Instead, the results diverge from each other.
NIST’s Xenos machine hopes to solve that problem. The system from NIST measures 3.3 x 3.3 x 3.4 meters and weighs almost 20,000 pounds. It makes use of touch probes, which measure the distances between points on an object in three dimensions. It has billionths of a meter in terms of sensitivities.
Applications for this machine include manufacturers of ultra-precision parts. Experiments with the machine will start this spring. The system should be complete within two years. “There are a lot of other things we need to learn before we design and perform measurements for the big G experiment,” said Vincent Lee of NIST’s Physical Measurement Laboratory (PML).
A group of researchers have reported new findings on the development of hyperspectral infrared nanoimaging, a technology that enables imaging of chemical composition with nanoscale spatial resolution.
The research group includes CIC nanoGUNE, Ikerbasque, Cidetec, and the Robert Koch-Institut. They have advanced a technology called Fourier transform infrared nanospectroscopy (nano-FTIR).
This technology falls under the category of infrared (IR) vibrational spectroscopy. This technique is used for the characterization of chemicals, materials and structures. But IR vibrational spectroscopy has diffraction limits.
However, the IR diffraction limit can be overcome with nano-FTIR. This optical technique combines scattering-type scanning near-field optical microscopy (s-SNOM) and Fourier transform infrared (FTIR) spectroscopy. FTIR is a technique that is used to obtain the infrared spectrum of a sample. Meanwhile, s-SNOM is a microscopy technique, which breaks the far field resolution limit. This is done by exploiting the properties of evanescent waves.
The combination technique also makes use of atomic force microscopy (AFM). In the flow, the tip of the AFM is illuminated with a broadband infrared laser or a synchrotron. Then, the backscattered light is analyzed with a Fourier transform spectrometer. Generally, the spatial resolution is in the range of 10nm to 30nm.
The problem? Due to the long acquisition times, the technology can only image point spectra or spectroscopic line scans.
In response, researchers have advanced this technology and developed nano-FTIR. “It is based on recording and stitching together multiple bandwidth-limited nano-FTIR spectra at each pixel of a 2D sample area, which is enabled by sample drift correction during data acquisition,” according to a paper from researchers. “Specifically, we use a tunable DFG laser continuum (350 cm−1 effective bandwidth) to record nanoscale-resolved hyperspectral infrared images.”
The technology records two-dimensional arrays of nano-FTIR spectra. This was done in a few hours and with a spatial resolution better than 30nm. “The excellent data quality allows for extracting nanoscale-resolved chemical and structural information with the help of statistical techniques (multivariate data analysis) that use the complete spectroscopic information available at each pixel,” said Iban Amenabar, a researcher.
“With the rapid development of high-performance mid-infrared lasers and by applying advanced noise reduction strategies, we envision high-quality hyperspectral infrared nanoimaging in a few minutes,” said Rainer Hillenbrand, another researcher on the project. “We see a large application potential in various fields of science and technology, including the chemical mapping of polymer composites, pharmaceutical products, organic and inorganic nanocomposite materials or biomedical tissue imaging.”