On the Mechanism of Volatilization of Large Biomolecules by Pulsed Laser Ablation of Frozen Aqueous Solutions
Previously we reported the volatilization of intact DNA molecules as large as ~ 410,000 Da by pulsed laser ablation of frozen aqueous solutions deposited on a copper substrate . The laser wavelength was 581 nm and the pulse length was 20 ns (full width). More recently, we have reported volatilization of DNA molecules up to ~ 6 MDa molecular weight , and the detection of molecular ions of DNA up to ~ 18,500 Da using a time of flight mass spectrometer [2,3]. The efficiency of ionization was found to increase when the laser was tuned to either 589 or 578 nm. In this paper we assemble information from these two studies, together with additional observations, in order to develop some understanding of the ablation (and ionization) mechanisms.
KeywordsMach Number Pulse Laser Ablation Lower Laser Power Laser Power Density Multiphoton Ionization
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