text: The research in his molecular spectroscopy laboratory focused on the discovery and elucidation of excitation mechanisms, with particular application to photochemical and biophysical problems. His most important achievements include identifying triplet states as source of phosphorescence emission, formulating the Kasha rule on fluorescence, and his work on singlet molecular oxygen.
  Kasha is also known for his interest in improving the sound quality and durability of the acoustic guitar and the classic string instruments.  A 30-year collaboration with luthier Richard Schneider led to a series of innovative changes to the traditional classical guitar. His guitar design was patented  and is known as the "Kasha guitar".