Laser -induced Desorption and Photofragmentation of Di - tert-butyl Peroxide Adsorbed on Surfaces

The laser- induced desorption and fragmentation of di - tert - butyl peroxide （DTBP） adsorbed on the Ag （110K） and quartz （130K） surfaces are investigated using time -resolved mass spectrometric technique. The time - of - flight （TOF） spectra of desorbed and dissociated products are measured at different laser fluences. The analysis of TOF spectra show that the UV laser - induced desorption of multilayer of DTBP on Ag surface proceeds via both photochemical desorption and thermal desorption at lower fluence,and the primary photodissociation occurs with rupture of the weak O-O bond at high laser fluence. For the DTBP/quartz system, the laser-induced photodesorption and fragmentation with two different channels take place i. e.
\beginaligned & \left(\mathrmCH_3\right)_3 \mathrmCOOC\left(\mathrmCH_3\right)_3(\mathrmads) \xrightarrow\mathrmhv\left(\mathrmCH_3\right)_3 \mathrmCOOC\left(\mathrmCH_3\right)_3(\mathrm~g) \\ & \left(\mathrmCH_3\right)_3 \mathrmCOOC\left(\mathrmCH_3\right)_3(\mathrmads) \xrightarrow\mathrmhv 2\left(\mathrmCH_3\right)_3 \mathrmCO \cdot _(\mathrmg) \longrightarrow 2\left(\mathrmCH_3\right)_2 \mathrmCO_(\mathrmg,+\mathrmCH_3 \cdot _(\mathrmg) \\ & \left(\mathrmCH_3\right)_3 \mathrmCOOC\left(\mathrmCH_3\right)_3(\mathrmads) \xrightarrow\mathrmhu\left(\mathrmCH_3\right)_3 \mathrmCOO \cdot _(\mathrmg)+\cdot \mathrmC\left(\mathrmCH_3\right)_3(\mathrm~g)\endaligned