“…The parent peaks of CFI 3 ( m / z = 412), CF 2 I 2 ( m / z = 304), and C 2 F 4 I 2 ( m / z = 354) could not be monitored because the UTI model 100C mass spectrometer is only capable of monitoring mass fragments up to 300. Previous γ-radiolysis studies of CF 3 I have identified CF 2 I 2 , C 2 F 5 I, C 2 F 4 I 2 , and C 2 F 6 as radiolysis products of CF 3 I. − Our identification of CFI 3 , however, represents a new finding. 4 Postirradiation (40 eV electrons at a fluence of 2 × 10 15 cm -2 ) temperature-programmed desorption data of CF 3 I multilayers (four layers) showing the desorption of C 2 F 6 , C 2 F 5 I, CF 2 I 2 , C 2 F 4 I 2 , I 2 , and CFI 3 .…”
Section: Resultsmentioning
confidence: 67%
“…This procedure allowed for the detection of radiolysis product desorption peaks at temperatures above 160 K that would have been too small to detect in the presence of the large CF 3 I multilayer and monolayer peaks. In identifying the radiolysis products, the results of the postirradiation temperature-programmed desorption experiments were also compared to previously identified γ-radiolysis products − of CF 3 I: I 2 , CF 4 , C 2 F 6 , CF 2 I 2 , C 2 F 5 I, and C 2 F 4 I 2 . To further verify the identification of radiolysis products, the desorption temperature and boiling point trends of the radiolysis products were also compared.…”
Section: Resultsmentioning
confidence: 99%
“…This procedure allowed for the detection of radiolysis product desorption peaks at temperatures above 160 K that would have been too small to detect in the presence of the large CF 3 I multilayer and monolayer peaks. In identifying the radiolysis products, the results of the postirradiation temperatureprogrammed desorption experiments were also compared to previously identified γ-radiolysis products [38][39][40][41][42][43][44] The results of postirradiation temperature-programmed desorption experiments discussed above do not provide evidence for CF 4 , a previously known γ-radiolysis product of CF 3 I. [38][39][40]43 The failure to identify CF 4 as a radiolysis product of CF 3 I may be attributed to a combination of three factors: (1) CF 4 does not have a parent peak (m/z ) 88) in its mass spectrum, (2) the other mass spectral fragments (CF 3 + , CF 2 + , CF + , and F + ) of CF 4 are also fragments of CF 3 I, 37 and (3) CF 4 has a lower desorption temperature than CF 3 I.…”
Section: B Identification Of Cf 3 Radicalsmentioning
confidence: 99%
“…In identifying the radiolysis products, the results of the postirradiation temperatureprogrammed desorption experiments were also compared to previously identified γ-radiolysis products [38][39][40][41][42][43][44] The results of postirradiation temperature-programmed desorption experiments discussed above do not provide evidence for CF 4 , a previously known γ-radiolysis product of CF 3 I. [38][39][40]43 The failure to identify CF 4 as a radiolysis product of CF 3 I may be attributed to a combination of three factors: (1) CF 4 does not have a parent peak (m/z ) 88) in its mass spectrum, (2) the other mass spectral fragments (CF 3 + , CF 2 + , CF + , and F + ) of CF 4 are also fragments of CF 3 I, 37 and (3) CF 4 has a lower desorption temperature than CF 3 I.…”
Section: B Identification Of Cf 3 Radicalsmentioning
The surface-induced and electron-induced chemistry of trifluoroiodomethane (CF3I), a potential replacement
for chlorofluorocarbons (CFCs) and chlorofluorobromocarbons (halons), were investigated under ultrahigh
vacuum conditions (p ∼ 1 × 10-10 Torr) on Mo(110). Results of temperature-programmed desorption (TPD)
experiments indicate that dissociative adsorption of CF3I leads only to nonselective decomposition on Mo(110), in contrast to reactions of CF3I on other metal surfaces. Desorption of CF3 radicals and atomic iodine
was detected mass spectrometrically during low-energy (10−100 eV) electron irradiation of four monolayer
thick films of CF3I condensed at 100 K. Results of postirradiation temperature-programmed desorption
experiments were used to identify CF2I2, C2F5I, C2F6, C2F4I2, and CFI3 as electron-induced reaction products
of CF3I. Except for CFI3, all of these electron-induced reaction products of CF3I have been previously identified
in γ-radiolysis studies, supporting our earlier claim that temperature-programmed desorption experiments
conducted following low-energy electron irradiation of multilayer thin films provide an effective method to
investigate the effects of high-energy radiation, including radical−radical reactions.
“…The parent peaks of CFI 3 ( m / z = 412), CF 2 I 2 ( m / z = 304), and C 2 F 4 I 2 ( m / z = 354) could not be monitored because the UTI model 100C mass spectrometer is only capable of monitoring mass fragments up to 300. Previous γ-radiolysis studies of CF 3 I have identified CF 2 I 2 , C 2 F 5 I, C 2 F 4 I 2 , and C 2 F 6 as radiolysis products of CF 3 I. − Our identification of CFI 3 , however, represents a new finding. 4 Postirradiation (40 eV electrons at a fluence of 2 × 10 15 cm -2 ) temperature-programmed desorption data of CF 3 I multilayers (four layers) showing the desorption of C 2 F 6 , C 2 F 5 I, CF 2 I 2 , C 2 F 4 I 2 , I 2 , and CFI 3 .…”
Section: Resultsmentioning
confidence: 67%
“…This procedure allowed for the detection of radiolysis product desorption peaks at temperatures above 160 K that would have been too small to detect in the presence of the large CF 3 I multilayer and monolayer peaks. In identifying the radiolysis products, the results of the postirradiation temperature-programmed desorption experiments were also compared to previously identified γ-radiolysis products − of CF 3 I: I 2 , CF 4 , C 2 F 6 , CF 2 I 2 , C 2 F 5 I, and C 2 F 4 I 2 . To further verify the identification of radiolysis products, the desorption temperature and boiling point trends of the radiolysis products were also compared.…”
Section: Resultsmentioning
confidence: 99%
“…This procedure allowed for the detection of radiolysis product desorption peaks at temperatures above 160 K that would have been too small to detect in the presence of the large CF 3 I multilayer and monolayer peaks. In identifying the radiolysis products, the results of the postirradiation temperatureprogrammed desorption experiments were also compared to previously identified γ-radiolysis products [38][39][40][41][42][43][44] The results of postirradiation temperature-programmed desorption experiments discussed above do not provide evidence for CF 4 , a previously known γ-radiolysis product of CF 3 I. [38][39][40]43 The failure to identify CF 4 as a radiolysis product of CF 3 I may be attributed to a combination of three factors: (1) CF 4 does not have a parent peak (m/z ) 88) in its mass spectrum, (2) the other mass spectral fragments (CF 3 + , CF 2 + , CF + , and F + ) of CF 4 are also fragments of CF 3 I, 37 and (3) CF 4 has a lower desorption temperature than CF 3 I.…”
Section: B Identification Of Cf 3 Radicalsmentioning
confidence: 99%
“…In identifying the radiolysis products, the results of the postirradiation temperatureprogrammed desorption experiments were also compared to previously identified γ-radiolysis products [38][39][40][41][42][43][44] The results of postirradiation temperature-programmed desorption experiments discussed above do not provide evidence for CF 4 , a previously known γ-radiolysis product of CF 3 I. [38][39][40]43 The failure to identify CF 4 as a radiolysis product of CF 3 I may be attributed to a combination of three factors: (1) CF 4 does not have a parent peak (m/z ) 88) in its mass spectrum, (2) the other mass spectral fragments (CF 3 + , CF 2 + , CF + , and F + ) of CF 4 are also fragments of CF 3 I, 37 and (3) CF 4 has a lower desorption temperature than CF 3 I.…”
Section: B Identification Of Cf 3 Radicalsmentioning
The surface-induced and electron-induced chemistry of trifluoroiodomethane (CF3I), a potential replacement
for chlorofluorocarbons (CFCs) and chlorofluorobromocarbons (halons), were investigated under ultrahigh
vacuum conditions (p ∼ 1 × 10-10 Torr) on Mo(110). Results of temperature-programmed desorption (TPD)
experiments indicate that dissociative adsorption of CF3I leads only to nonselective decomposition on Mo(110), in contrast to reactions of CF3I on other metal surfaces. Desorption of CF3 radicals and atomic iodine
was detected mass spectrometrically during low-energy (10−100 eV) electron irradiation of four monolayer
thick films of CF3I condensed at 100 K. Results of postirradiation temperature-programmed desorption
experiments were used to identify CF2I2, C2F5I, C2F6, C2F4I2, and CFI3 as electron-induced reaction products
of CF3I. Except for CFI3, all of these electron-induced reaction products of CF3I have been previously identified
in γ-radiolysis studies, supporting our earlier claim that temperature-programmed desorption experiments
conducted following low-energy electron irradiation of multilayer thin films provide an effective method to
investigate the effects of high-energy radiation, including radical−radical reactions.
“…Because CF 2 I 2 has a higher boiling point (374 K) than C 2 F 6 (195 K), C 2 F 5 I (286 K) and C 2 F 3 I (303 K) [20], our identification of CF 2 I 2 is consistent with the thermal desorption trend for the following four species: C 2 F 6 (120 K), C 2 F 5 I (160 K), C 2 F 3 I (165 K) and CF 2 I 2 (185 K). In addition to being previously identified as a γ -radiolysis product of CF 3 I [17,23,24], CF 2 I 2 has also been identified as an electroninduced radiolysis product of CF 3 I at incident electron energies above the ionization threshold [16,22]. 2 ) appearing at ∼235 K in the post-irradiation thermal desorption data for CF 3 I was assigned to the radiolysis product CFI 3 .…”
The dynamics of electron-induced reactions in condensed trifluoroiodomethane (CF3I) were studied under ultrahigh vacuum conditions. Seven CF3I radiolysis products (C2F6, C2F5I, C2F3I, CF2I2, C2F4I2, CFI3 and C2F3I3) were identified using temperature-programmed desorption experiments conducted after irradiation with 4 eV electrons. Although C2F6 formation at energies above 4 eV is ascribed to electron-induced electronic excitation followed by prompt dissociation of the C-I bond to form [Formula: see text] radicals that dimerize, the formation of the other six radiolysis products at low sub-ionization incident electron energies is attributed to dissociative electron attachment (DEA) because of the observed resonance peaks in the radiolysis product yields as functions of incident electron energy (∼2 to ∼ 7 eV). All seven CF3I electron-induced reaction products were also identified following irradiation with 500 eV electrons. While dissociative electron attachment and/or electron impact excitation may play an important role in the high-energy radiation-induced synthesis of the high-yield product C2F6, a dramatic enhancement of up to ∼ 2 × 10(4) in product yield per electron at 500 eV relative to that at 4 eV for some products suggests, however, that DEA is not the dominant mechanism for the high-energy radiation-induced synthesis of those products.
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