Lock-in amplification using ac modulation and second-harmonic detection is routinely employed in such techniques as ac polarography, ac voltammetry, and inelastic electron tunneling spectroscopy (IETS). Properties of the modulation source are shown in the present IET studies to limit the obtainable signal-to-noise ratio of a spectrum. A single inelastic electron tunneling junction is used to demonstrate the effect of various commercial modulation sources on the IET spectrum of benzoic acid on alumina. With all other parameters being held constant, the signal-to-noise ratio of the IET spectrum is found to be inversely correlated with the total harmonic distortion of the modulation source.

PDF Article

Cited By

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
Login to access OSA Member Subscription