Short-lived isomers in the nuclei 90, 92Nb ' 99Mo ' 98,1oo, lOlTc and l~ populated in photonuclear reactions were studied by pulsed beam techniques. Energy and half-life of the 7-rays deexciting the isomeric levels were measured by recording energy-time spectra. The delayed y-rays and K X-rays were detected by means of an intrinsic Ge-detector of high resolution. From the measured intensity ratios internal conversion coefficients were determined. The multipolarities of the isomeric transitions could be deduced in most cases. A classification of the observed isomers has been tried on the basis of the obtained experimental results and most recent literature data.