  A new method for high-sensitivity subwavelength spectromicroscopy is proposed
based on the usage of a spaser (near-field laser) in the form of a scanning
probe microscope tip. The high spatial resolution is defined by the tip's
curvature, as is the case for apertureless scanning near-field optical
microscopy. In contrast to the latter method, we suggest using radiationless
plasmon pumping by neighbouring quantum dots instead of irradiation of the tip
by an external laser beam. The spaser generation spectrum is analyzed. The
plasmon generation is suppressed due to absorption at the transition
frequencies of the neighbouring nano-objects (molecules or clusters) under
study. As a result, narrow dips appear in the wide plasmon generation spectrum.
Further, the highest sensitivity is achieved near the spaser generation
threshold. The sensitivity of the spaser spectromicroscope is estimated.
