Indian Journal of Pure & Applied Physics Vol. 44, April 2006, pp 320-324 Spectral distribution and enhancement studies of (ZnS+HgO) base electroluminophor Sudhir Kumar Srivastava & Laxmi Kant Singh Department of Physics and Electronics, Dr.Ram Manohar Lohia Avadh University, Faizabad 224 001 Received 7 October 2004; revised 18 October 2005; accepted 2 January 2006 The enhancement effect of dielectric dispersed double band emitting (ZnS+HgO):Cu,Mn(H) electroluminescent material has been investigated under the concurrent excitation of ac fields and 3650 Å UV-radiation. The emissions in yellow region were found to show relatively larger enhancement than that in case of green emission. The instantaneous behaviour of the individual peaks (green and yellow) was critically recorded and was observed that both the emissions isolately behave almost similarly and exhibit an exponential decay or rise before attaining the saturation value. The maximum enhancement is always found to be less than 4/3. Keywords: Luminescence, Electroluminescence, Photoluminescence IPC Code: C09K 11/00 1 Introduction The enhancement of luminescence by the combination of radiation and electric fields on phosphor materials is now well-known. X-ray induced enhancement effect was first reported by Destriau 1 in case of manganese activated (ZnS+CdS) phosphor. Cusano 2 studied this phenomenon under the simultaneous action of electric field and UV- radiations or X-rays on ZnS:Mn(Cl) and ZnS:P, As or Sb(Cl). Similar behaviour of poly-crystalline phosphors dispersed in suitable dielectric was studied by Patek 3 , Ballentyne 4 and Thornton 5 using ultraviolet radiation as one of the stimulating agency along with the electric field. Woods 6 studied these enhancement effects in self-activated single crystals of ZnS. The behaviour of blue and green band emitting ZnS electroluminophor has been investigated by Prakash 7 and Singh 8 . Singh 9 studied the tri-colour emitting (blue, green and yellow) ZnS electroluminophor activated by Cu and Mn and co-activated by hydrogen, under the joint action of ac fields and UV- radiations. Prakash 10 also studied the ultraviolet enhancement effect for a set of ZnO phosphors at various temperatures. Shukla 11 studied also the ultra- violet induced enhancement effect on ZnO:Cu, Mn(H) at various excitation fields and with different manganese concentrations. The experimental findings of radiation enhancement of the double band emitting (green and yellow) (ZnS+HgO):Cu, Mn(H) electroluminophor have been studied in the present paper. The time dependent instantaneous behaviour of electroluminescent emission has been studied under the joint action of ac electric field and 3650 A 0 UV- radiation. 2 Experimental Details The phosphor was activated with copper (in form of CuSO 4 ) and manganese (in form of MnCl 2 ) simultaneously. The co-activation of hydrogen was done by firing the sample in reduced atmosphere of hydrogen for about one hour at the temperature of around 1100°C. During the phosphor preparation an autovariac was used for varying voltages to get the desired temperatures in Kanthal wire wound furnace of silica (1 metre length. and 8 cm. diametre). The phosphor was kept in loosely capped silica tube (10 cm. length. 10 mm. diametre). The electroluminescent panels used in these investigations were of the usual parallel plate capacitor type. Powdered electroluminescent phosphors were dispersed in castor oil and pressed on polished aluminium plate, over which a conducting transparent mica sheet was placed to serve as an usual electrode.