Why did Bloembergen use masers for spectroscopy?
I used masers—precursors to lasers—because they provided coherent, monochromatic radiation, which was essential for high-resolution spectroscopy. In the 1950s, masers offered a stable source for studying relaxation phenomena in solids and gases. For example, I applied them to measure spin-lattice relaxation times in crystals, which revealed how energy dissipates. Later, with lasers, I extended this to nonlinear optics, where coherence allowed us to observe effects like the stimulated Raman effect. The beauty of physics is in its surprises: masers and lasers turned spectroscopy from a passive observation into an active manipulation of matter.
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