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A scanning tunneling microscope {STM) has been used to measure energy gaps in the chargedensity-wave (CDW) phases of the layer-structure dichalcogenides and in the high-temperature superconductor Bi&Sr,CaCu&08. Measured values of Ac& at 4.2 K for 2H-TaSe"2H-TaS"and 2H-NbSe2 are 80, 50, and 34 meV giving values of 26C&/k& T, equal to 15.2, 15.4, and 23.9, indicating strong coupling in these CDW systems. Measured values of 6&. & at 4.2 K in 1T-TaSe. and 1T-TaS, are -150 meV for both materials giving 2hcp~/k~r, . =5.8. STM scans of Bi,Sr,CaCu. O, at 4.2 K resolve atoms on the BiO"layer and show possible variations in electronic structure. The energy gap determined from I versus V and dI/d V versus V curves is in the range 30 -35 meV giving values of 2A/kBT, =8. Spectroscopy measurements with the STM can exhibit large zero-bias anomalies which complicate the analysis of the energy-gap structure, but adequate separation has been accomplished.

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