One of the most important and groundbreaking applications of Raman spectroscopy is detecting materials associated with signs of life and organic chemistry. Gypsum, a sulfate mineral found on Mars, is closely associated with water and has been known to harbor fossil life on Earth. Apatite is made of calcium phosphates, and phosphates can be evidence of life because they are part of the backbone of DNA. Scientists believe that the first life on Earth may have been formed near volcanic seeps in seawater, a sulfur-rich environment. Calcite is also important to life because L- and D-amino acids are known to adsorb to this mineral.
Below we compare the results from our instruments (blue) to the data published on the RRUFF online database (red).
This summer research project greatly expanded upon the work done previously by Brett Berger in his Senior Thesis (see work here). In Berger’s device, however, the current increased exponentially with the input voltage, making the laser quite unstable. This summer’s group came up with an op-amp circuit design that would be controlled by a potentiometer and provided a linear relationship between the current and voltage. After weeks of testing, the team found that though the current was stable, the temperature and power output of the laser greatly fluctuated with time, also making the laser unstable. This also posed a potential threat to the laser and/or sample, as they may overheat and be damaged. In the future, the lab hopes to design a temperature-control circuit that will not greatly cut down on the power output of the laser. Below is a diagram of the circuit implemented:
In order to make the instrument adaptable, the team also made changes to the instrument itself. A new stage was designed to hold a cuvette for liquid samples, a slide for solid samples, and a power meter to measure the laser power output. The team also stationed the spectrometer inside a box with the inside painted black in order to minimize background noise in the spectra and to absorb any laser light that may bounce and reflect. Below is a photograph of the adapted instrument:
Meet the summer research students of 2015! Yvonne Ban is a physics major of the class of 2017, interested in astrophysics. Viviana Bermudez is a prospective engineering major of the class of 2018. During the first few days of research, they came up with an official name for the HMC Astrobiology lab: Extraterrestrial Vehicle Instrumentation Lab, a.k.a. EVIL.