Quantitative Micro-Raman Spectroscopy for Partial Pressure Measurement in Small Volumes

Area of Science:

• Physics
• Materials Science
• Analytical Chemistry

Background:

• Accurate pressure measurement is crucial for microscale devices.
• Microelectromechanical systems (MEMS) atomic vapor cells require precise internal gas characterization.
• Nondestructive techniques are preferred for sensitive microscale components.

Purpose of the Study:

• To demonstrate Raman confocal microscopy for quantitative gas pressure measurement.
• To apply this method for characterizing nitrogen partial pressure in MEMS atomic vapor cells.
• To validate the technique against established spectroscopic methods.

Main Methods:

• Utilizing Raman confocal microscopy for gas analysis.
• Developing a calibration procedure for pressure quantification.
• Comparing results with rubidium hyperfine frequency spectroscopy.

Main Results:

• Quantitative partial pressure measurements of molecular gases in sealed mm³ volumes.
• Successful characterization of absolute nitrogen partial pressure in MEMS atomic vapor cells.
• Good agreement between Raman microscopy and rubidium spectroscopy measurements.
• Achieved a three-sigma detection limit below 10 mbar with a 1-hour integration time.

Conclusions:

• Raman confocal microscopy is a viable nondestructive method for small-scale pressure measurements.
• The technique offers precise characterization of gas environments within MEMS devices.
• This approach provides a valuable tool for developing advanced atomic clocks and other microdevices.