fragmentation study of the Rhodamine 610 cation using visible-laser desorption ionization

The fragmentation of a potential visible matrix-assisted laser desorption ionization: Rhodamine 610 was studied under 532 nm visible irradiation, as a function of anion counter ion. It was found that at a fixed fluence, the chloride salt produced fewer fragments than those formed with ClO₄ ⁻ or BF₄ ⁻. Evidence presented suggests that the degree of fragmentation is inversely proportional to the strength of the contact ion pair in the solid state; that is, more energy is deposited into the radical cation which can lead to fragmentation when less energy is required to separate the ion pair. Similar results were found for salts of Rhodamine 6G. Copyright © 2010 John Wiley & Sons, Ltd.