Sample interview questions: Describe the principles behind laser-induced breakdown spectroscopy and its applications in forensics.
Sample answer:
Laser-Induced Breakdown Spectroscopy (LIBS)
LIBS is a spectroscopic technique that utilizes high-energy laser pulses to excite and vaporize a small amount of a sample. The resulting plasma emits light at characteristic wavelengths that correspond to the elements present in the sample. This spectrum can be analyzed to determine the composition of the sample.
Principles of LIBS:
- A high-energy laser pulse (typically from a Q-switched Nd:YAG laser) is focused on the sample surface.
- The intense laser energy vaporizes a small amount of the sample, creating a plasma.
- The plasma contains excited atoms and ions, which emit light at specific wavelengths upon relaxation.
- A spectrometer is used to capture the emitted light and measure its spectrum.
Applications in Forensics:
LIBS has gained significant traction in forensic science due to its:
- Rapid analysis: Samples can be analyzed in situ without extensive preparation.
- Non-destructive nature:… Read full answer