In science fiction, a disintegrator ray is an energy beam that destroys an object by disintegrating it to its basic components, which usually disperse into the atmosphere. Ray gun is the generic term for the weapons that fire disintegrator beams.
The disintegrator gun’s first literary appearance was in Edison's Conquest of Mars (1898), the sequel novel to Fighters from Mars an unauthorized contemporary interpretation of The War of the Worlds (1898), by H.G. Wells:
I had the good fortune to be present when this powerful engine of destruction was submitted to its first test. We had gone upon the roof of Mr. Edison's laboratory and the inventor held the little instrument, with its attached mirror, in his hand. We looked about for some object on which to try its powers. On a bare limb of a tree not far away, for it was late fall, sat a disconsolate crow.
"Good," said Mr. Edison, "that will do. . . ."
Instantly there was another adjustment of the index, another outshooting of vibratory force, a rapid up and down motion of the index to include a certain range of vibrations, and the crow itself was gone — vanished in empty space! There was the bare twig on which a moment before it had stood. Behind, in sky, was the white cloud against which its black form had been sharply outlined, but there was no more crow.
In the sequel, this was Earth’s counter-weapon against the Martian “Heat-Ray” from The War of the Worlds.
Larry Niven's Known Space series features a disintegrator that works by suppressing the charge on the electron. As a result, the molecules along the beam path dissociate as the mutual electrostatic repulsion between the positively charged atomic nuclei drives the nuclei apart. This weapon appears in the novel World of Ptavvs (1966).
One alternative approach would be to suppress the strong nuclear force, causing atomic nuclei to blow themselves apart as the protons repelled each other.