Electronic radiation effects in water ice and other insulators

This thesis describes a broad study of insulator properties. We utilized various surface analysis techniques to investigate the surface electronic properties of insulators and the effects of irradiation with energetic electrons and ions. Electronic irradiation of insulators is a common phenomenon and can be found in fields ranging from semiconductor device manufacturing to space physics.; Water ice displayed several new features that have not been measured previously. Electronic radiation proved ineffective in altering the water ice surface except at large doses (∼1020 e·/cm 2). With large current densities, we eroded water ice films and measured sputtering yields due to electrons of ∼0.5 x 10-6 to 3.4 x 10-6 molecules per electron. Large doses did cause damage sites to be produced within the band gap, specifically an OH- band at 5.5 eV. We identified the excited H 2O+ to 4a1 transition. We also measured an autoionization process due to a 2a1 to 4a1 transition. Measuring secondary electron emission (SEE) spectra for the first time, we determined the valence level of the autoionization electron as a convolution of the valence states.; Our study of silicon dioxide provided confirmation of the creation of suboxides on the surface by ion irradiation and the subsequent reconstruction of the SiO2 surface by electron irradiation. Using electron energy loss spectroscopy (EELS) in conjunction with Auger electron spectroscopy (AES), we could identify the probable surface transitions due to SiO2. We could observe the different effect of electronic radiation before and after ion irradiation.; For the first time, we measured the EELS spectra of polytetrafluoroethylene and compared them to the X-ray photoelectron spectroscopy (XPS) spectra. We attributed the surface states to mixed C 2p and F 2p states. We also measured the sensitivity of polytetrafluoroethylene (PTFE) to irradiation by electrons and ions. The dramatic loss of surface states was correlated to the loss of fluorine and the creation of CFx compounds during irradiation.; Overall, this thesis demonstrates the usefulness of the different surface spectroscopies in the study of insulator surfaces. EELS proved especially important because of its relative insensitivity to surface charging. Also, EELS is effective at detecting the surface states of insulators and measuring the changes caused by ion and electron bombardment. Used together with other spectroscopies like XPS and AES, EELS is a valuable tool in the study of the surface electronic states of insulators.