Lin , Siebrand , and Englman & Jortner are among the celebrated who are credited with developing the foundations for internal conversion that are used today. However, it was not just them; decades of blood, sweat, and tears, from an army of dedicated researchers working to build the foundations we all know. The renowned energy gap law, for example, could not have come to pass without Lin laying the ground work, the photophysical observations of Kasha , or the unique observations of Robinson & Frosch . Following all this work was the experimental validation over the years , solidifying the theory presented, which allowed for many others to improve on the work, like Plotnikov , Valiev and co-workers , Shaw and co-workers , and Manian and co-workers , to calculate explicit coupling terms and occupational quanta (quantum occupation of vibrational normal modes). Inspired by the theoretical development, cutting edge light-emitting diodes and solar cell devices demonstrate that full control over internal conversion is vital to truly perfect device efficiency.