Precision cavity enhanced velocity modulation spectroscopy

The new technique of cavity enhanced velocity modulation spectroscopy has been further developed, incorporating a tighter cavity to laser lock and an optical frequency comb for absolute frequency calibration. Several N2 transitions have been observed with much higher precision than previously possible, and transitions that were blended in earlier Doppler-limited experiments are now resolved. The full-width at half-maximum of the observed Lamb dips is 40 MHz, and appears to be dominated by a broadening due to the velocity modulation. Future extension of this technique into the mid-infrared should enable significant improvements in the sensitivity and resolution of vibrational spectroscopy of molecular ions. 2010 Elsevier B.V. All rights reserved.