Typically only a fraction of spins is excited in electron paramagnetic resonance (EPR)spectroscopy, with this fraction being particularly small for metal centers. Compared to hypothetical experiments that excite all spins in an optimal manner with respect to their relaxation behavior, the established experimental schemes entail a large reduction in sensitivity. This reduction results from the problem that even with the shortest achievable rectangular pulses and the highest achievable microwave powers, excitation bandwidth is much smaller than typical spectral widths. With the advent of arbitrary waveform generators with time resolution in the microwave range during the past few years, this problem can potentially be solved by variation of the excitation frequency throughout the whole required range. However, such an approach requires redesign of existing experiments or even design of new experiments from scratch to obtain the same information as before with higher sensitivity. In addition, the excitation waveform needs to be optimized with respect to the technical parameters of the spectrometer and to the properties of the spin system. The proposed project aims to develop such new experimental schemes and to introduce general methodology for such developments.