Terahertz molecular spectroscopy studies matter using terahertz radiation.
This radiation lies between microwaves and infrared light.
It occupies the frequency range from 0.1 to 10 terahertz.
Molecules interact strongly with terahertz waves.
These waves excite rotational and low-frequency vibrational modes.
As a result, each molecule shows a unique spectral fingerprint.
The technique is non-ionizing.
Therefore, it is safe for sensitive materials.
Biological samples remain largely undamaged.
Terahertz spectroscopy is highly sensitive.
It can detect weak intermolecular forces.
Hydrogen bonding becomes clearly visible.
Water plays a major role in terahertz measurements.
Its strong absorption affects spectral interpretation.
However, this property is useful in studying hydration dynamics.
Time-domain terahertz spectroscopy is widely used.
It measures both amplitude and phase.
This allows direct calculation of refractive index and absorption.
The method requires ultrafast lasers.
Photoconductive antennas generate terahertz pulses.
Detectors capture the transmitted or reflected signal.
Applications are rapidly expanding.
Pharmaceuticals use it for polymorph identification.
Security agencies apply it for chemical detection.
In materials science, it probes semiconductors.
Carrier dynamics can be studied in real time.
Thin films are analyzed without contact.
Astrophysics also benefits from this technique.
Many interstellar molecules emit terahertz radiation.
Spectroscopy helps identify them in space.
Terahertz molecular spectroscopy bridges physics and chemistry.
It reveals motions hidden to other methods.
Its importance continues to grow with advancing technology.