Avoided Level Crossing Muon Spectroscopy of Free Radicals Formed by Muonium Addition to the Constituents of DNA

Penny L. Hubbard, Vasily Oganesyan, Nail Sulaimanov, Julea Butt, Upali A Jayasooriya

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Abstract

Avoided level crossing muon spectra (ALC-µSR) of the free radicals formed by muonium addition to nucleic acid bases adenine, cytosine, guanine, thymine, and uracil are reported and assigned by using ab initio DFT calculations. The following radicals and their hyperfine constants, Aµ, were identified: adenine, C8 (the radical formed by adding Mu to the C8 carbon of adenine) = 424.1 MHz; cytosine, C5 = 406.1 MHz and C6 = 593.0 MHz; guanine, C5 = 657.1 MHz and C8 = 407.5 MHz; thymine, C5 = 494.3 MHz and O2 = 409.7 MHz; and uracil, C5 = 381.7 MHz, C6 = 553.6 MHz, O2 = 418.1 MHz, and O4 = 149.7 MHz. No ALC-µSR resonances were observed from polycrystalline samples of the sugar ribose or potassium phosphate at 300 K. Preliminary ALC-µSR spectra of a double stranded (ds) DNA sample are reported and found to show additional resonances to those of the nucleic acid bases, indicating the behavior of implanted muons in dsDNA to be more complex than a simple sum of the behaviors found with the bases. The reported data are also pertinent to H atom adducts of these materials, where the hyperfine parameters are scaled by the ratio of the gyromagentic ratio of the muon to that of the proton.
Original languageEnglish
Pages (from-to)9302-9309
Number of pages8
JournalThe Journal of Physical Chemistry A
Volume108
Issue number42
DOIs
Publication statusPublished - 2004

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