VUV radiation

For ion TOF measurement a probe laser was used to ionize reaction products in the reaction zone. The (1 + F) resonance-enhanced multiphoton ionization (REMPI) method was adapted for H-atom detection. The necessary vacuum ultraviolet (VUV) radiation near 121.6 nm (for Lyman-a transition) can readily be generated by a frequency-tripling technique in a Kr cell.37 The sensitivity of this (1 +1 ) REMPI detection scheme is extremely high owing to the large absorption cross-section of Lyman-a transition,... 

The conditions required for the construction of these cells place considerable strain on the phosphors. This is because setting up the transparent electrodes requires annealing in the range 500-600 °C. Additionally the phosphors must be able to stand the constant ion bombardment from the plasma and VUV radiation. Most importantly, the phosphors must convert the VUV into visible light with maximum... 

Besides spectroscopic techniques such as infrared-reflection-absorption spectroscopy (IRRAS) and X-ray photoelectron spectroscopy (XPS), SFM-based stiffness imaging was applied in order to detect radiation-induced variations of surface stiffness [180]. For that purpose, when exposing the PE-film to the VUV-radiation, the film was covered with a Ni mesh. Thus, the PE-film was partially masked and exposed to the VUV radiation only within the square-shaped holes of the mesh. After having finished that treatment and having removed the mesh, the sample surface was scanned in force modula-... 

This process uses light irradiation of wavelengths lower than the UV-C, i.e., lower than 190 nm. Generally, Xe excimer lamps (Xexc = 172 nm) are used. The excitation leads, in the majority of the cases, to the homolytic breakage of chemical bonds, degrading OM in condensed and gaseous phases (for example, fluorinated and chlorinated hydrocarbons) [1,3]. However, its application is limited, and the most important use of VUV radiation is in water photolysis (Eq. 8) ... 

This calculation demonstrates that 99% of the incident 172 nm radiation (VUV radiation) is absorbed by water within a zone of a thickness I of 36.4 pm. This value represents the reaction zone ofVUV-initiated photochemistry in water (see Fig. 7-12). 

Radiometric quantities are important to describe and measure UV and VUV radiation. They are usually subdivided into energetic, spectral and photonic terms. Energetic terms (Tab. 3-9) are based on the energy of the radiation and they refer to all relevant wavelengths. Eor each of these terms a spectral derivative can be defined (Bolton, 1999) which is correlated with a specific wavelength X. Eor example, the extraterrestrial solar spectrum incident on the upper atmosphere is represented by the mean spectral irradiance Eq in W m nm over a defined wavelength interval AX in nm (CIE, 1989). Further, each of the spectral units can easily be transferred to photon-based units, which themselves are related to radio-metric units (cf Braun et al., 1991). 

Unlike the H2O2-UV process the VUV oxidation of organic substrates in water (H2O-VUV) is initiated by the photochemical homolysis of water producing a series of reactive species (cf Fig.s 5-9 and 7-3, and Equations 5-18 to 5-20). In many cases water itself is the prominent absorber of VUV radiation at 172 nm (cf Ex-... 

When exposed to gamma radiation both polymers had almost identical gel formation, so it was surprising that when treated with VUV radiation the response of each polymer was dramatically different (10,12). The homopolymer showed signs of surface crosslinking with little change to the bulk, while the TrFE copolymer had a degree of crosslinking consistent with VUV radiation... 

Spacecraft flying in LEO are exposed not only to neutral atomic and molecular species, but also high fluxes of vacuum ultraviolet (VUV) radiation and relatively low fluxes of ions, both of which might contribute to the degradation of materials present on spacecraft surfaces. ° It has been reported that fluorinated ethylene-propylene copolymer (FEP Teflon), which is used as a thermal blanketing material, erodes under the combined exposure of VUV light and atomic oxygen, while the erosion by... 

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