1. University of Arizona, Dept. of Physics
Molecular Spectroscopy of Rotational, Vibrational, and Electronic oscillations
Abram Young
University of Arizona, Dept. of Physics
J2,0 ← 1,0 Transition

3. Generation of THz waves by Optical Rectification

4. Reference pulse
Pulse through sample
Discrete Fourier Transform to recover spectrum and phase

6. THz signal through NH3 cell
11 cm cell with thin Mylar windows
Evacuated to <50 mTorr before each scan
Adjustable pressure 0.1 – 100 Torr
0.119 pSec shift from vacuum sample approximates index of refraction
NH3 Rotational transitions
Noise floor

7. Low Order Rotational Lines
J1,0 ←0,0 = THz (0.597 THz)
J2,0 ←1,0 = 1.215THz (1.193 THz)
J3,0 ←2,0 = 1.765THz (1.790 THz)

8. Future Measurements For room temperature Ammonia,
Sub-Doppler Lamb dip spectroscopy
Greatly reduced from atomic spectra due to greater reduced mass and lower oscillation frequency
For room temperature Ammonia,
~1.8 MHz for J1<-0 (3.6 MHz, 5 MHz for J2<-1 and J3<-2)

9. 5 Bands from 140GHz-900GHz Microlambda 10-20 GHz multilock Synth
Signal conditioning
DC supplies
5 Bands from 140GHz-900GHz
Microlambda GHz multilock Synth
Electronically Chopped Amplifier
Varying multiplication bands Rx Tx
sample