PT Journal AU Gershenzon, EM Gol'tsman, GN Karasik, BS Semenov, AD TI Measurement of the energy gap in the compound YBaCu[sub:3]O[sub:9-δ] on the basis of the IR absorption spectrum SO JETP Lett. JI JETP Lett. PY 1987 BP 237 EP 238 VL 46 IS 5 DE YBCO HTS detectors AB For the first time the long-wave infrared absorption spectrum has been measured by means of the bolometric effect and energy gap for high-temperature superconducting ceramics YBa/sub 2/Cu/sub 3/O/sub 9-delta/ has been determined from absorption threshold. 2delta/kT/sub c/ value is equal to 0.6. ER