8Th International Conf On Dynamical Processes In Excited States Of Solids ( Dpc 91 ), Date: AUG 27-31, 1991, Location: LEIDEN, NETHERLANDS, Sponsors: ROYAL NETHERLANDS ACAD ARTS & SCI, JOHN VANGEUNS FDN, ALGEMENE KUNSTZIJDE UNIE KONINKLIJKE ZOUT ORGANON, COHERENT, ELSEVIER, IBM NEDERLAND, LEIDS UNIV FONDS, PHILIPS NEDERLAND, OPTILAS, SHELL NEDERLAND, Host: UNIV LEIDEN