東華大學圖書館 |

語系: 繁體中文

說明(常見問題)

回圖書館首頁

手機版館藏查詢

登入

回首頁

切換: 標籤 | MARC模式 | ISBD

Radiation processing of water, oxyge...

Teolis, Benjamin D.

FindBook

Google Book

Amazon

博客來

Radiation processing of water, oxygen and ozone ices.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Radiation processing of water, oxygen and ozone ices./
作者:	Teolis, Benjamin D.
面頁冊數:	222 p.
附註:	Source: Dissertation Abstracts International, Volume: 68-02, Section: B, page: 1036.
Contained By:	Dissertation Abstracts International68-02B.
標題:	Physics, Condensed Matter. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3251385

Radiation processing of water, oxygen and ozone ices.
Teolis, Benjamin D.

Radiation processing of water, oxygen and ozone ices. - 222 p.

Source: Dissertation Abstracts International, Volume: 68-02, Section: B, page: 1036.

Thesis (Ph.D.)--University of Virginia, 2007.

This thesis investigates sputtering, radiolysis and structural changes produced by ion irradiation in H2O, O2 and O 3 ices using several experimental techniques: mass spectrometry, microbalance gravimetry, reflectance spectroscopy and sputter depth profiling. The first measurements of the angular dependence of the sputtering of water ice are presented, showing that (i) the sputtering yield exhibits a cos -1.3theta dependence on the incidence angle theta of the projectiles (100 keV protons) and (ii) that the sputtered flux of H2O is more forward directed than that of O2. Using 100 keV Ar + projectiles, a complex fluence dependence in the sputtered flux of O2 is also identified. The fluence dependence is determined by (i) the thermal and irradiation history of the water ice and (ii) the deposition of ice overlayers. These results are explained by the production of trapped O2 in the ice, with the O2 concentration being governed by the rates of production, diffusion and removal of O 2 from the ice surface by sputtering and/or thermal desorption. Sputter depth profile measurements show that the primary fluence dependence of O 2 sputtering is due to the accumulation of trapped O2, and that O2 is produced preferentially near the ice surface due to out-diffusion of hydrogen in the form of H2 from that region. Removal of O2 from the surface is blocked if H2O is condensed concurrently with Ar+ irradiation, resulting in an enhancement of the concentration of O2 in the ice which is sufficient for the generation of ozone. This result represents the first reported synthesis of ozone by radiolysis of pure water ice, and may help to explain the presence of O3 in the surfaces of icy satellites of Jupiter and Saturn, where sputtered and sublimed H2O recondense onto surfaces that are simultaneously subject to irradiation by magnetospheric ions.Subjects--Topical Terms:

1018743
Physics, Condensed Matter.

Radiation processing of water, oxygen and ozone ices.
LDR:05022nmm 2200289 4500 001 1829391
005 20071107102548.5
008 130610s2007 eng d
035 $a (UMI)AAI3251385
035 $a AAI3251385
040 $a UMI $c UMI
100 1 $a Teolis, Benjamin D. $3 1918251
245 1 0 $a Radiation processing of water, oxygen and ozone ices.
300 $a 222 p.
500 $a Source: Dissertation Abstracts International, Volume: 68-02, Section: B, page: 1036.
500 $a Adviser: Raul Baragiola.
502 $a Thesis (Ph.D.)--University of Virginia, 2007.
520 $a This thesis investigates sputtering, radiolysis and structural changes produced by ion irradiation in H2O, O2 and O 3 ices using several experimental techniques: mass spectrometry, microbalance gravimetry, reflectance spectroscopy and sputter depth profiling. The first measurements of the angular dependence of the sputtering of water ice are presented, showing that (i) the sputtering yield exhibits a cos -1.3theta dependence on the incidence angle theta of the projectiles (100 keV protons) and (ii) that the sputtered flux of H2O is more forward directed than that of O2. Using 100 keV Ar + projectiles, a complex fluence dependence in the sputtered flux of O2 is also identified. The fluence dependence is determined by (i) the thermal and irradiation history of the water ice and (ii) the deposition of ice overlayers. These results are explained by the production of trapped O2 in the ice, with the O2 concentration being governed by the rates of production, diffusion and removal of O 2 from the ice surface by sputtering and/or thermal desorption. Sputter depth profile measurements show that the primary fluence dependence of O 2 sputtering is due to the accumulation of trapped O2, and that O2 is produced preferentially near the ice surface due to out-diffusion of hydrogen in the form of H2 from that region. Removal of O2 from the surface is blocked if H2O is condensed concurrently with Ar+ irradiation, resulting in an enhancement of the concentration of O2 in the ice which is sufficient for the generation of ozone. This result represents the first reported synthesis of ozone by radiolysis of pure water ice, and may help to explain the presence of O3 in the surfaces of icy satellites of Jupiter and Saturn, where sputtered and sublimed H2O recondense onto surfaces that are simultaneously subject to irradiation by magnetospheric ions.
520 $a As in the case of water ice, the sputtering yields of solid O2 and O3 were found to depend on the occurrence of radiation chemistry in the solid. In solid O2, a fluence dependence in the sputtering yield was discovered (using 100 keV protons) and attributed to the production of trapped ozone, which enhanced the sputtering yield. The enhancement is due to the liberation of potential energy during radiolytic decomposition of O3 into O2, which contributes to the physical ejection of molecules from the solid; a physical phenomenon not previously observed in studies of sputtering. When irradiated O2 is warmed above &sim;33 K, the O2 desorbs from the solid, leaving behind residual solid ozone that was found to possess a remarkably low density (&sim;0.34 g/cm 3). The discovery of a low density form of solid ozone can explain the temperature dependence in the infrared spectra of condensed ozone previously reported, but the molecular structure of the solid and the reason for its transformation to a high density form at &sim;47 K are still open questions. Solid ozone was found to possess an extraordinarily high sputtering yield when irradiated by 100 keV protons at 30 K and above, second only to solid hydrogen. This is due to (i) the high chemical reactivity of the solid and (ii) the volatility of the decomposition product (O2).
520 $a Laboratory simulations of processes on astronomical surfaces that use infrared reflectance spectroscopy of thin films to analyze their composition and structure often ignore important optical interference effects which often lead to erroneous measurements of absorption band strengths and give an apparent dependence of this quantity on film thickness, index of refraction and wavelength. In appendix 1, these interference effects are demonstrated experimentally and the optical depths of several absorption bands of thin water ice films on a gold mirror are shown to be disproportionate to film thickness. A way to remove interference effects by performing measurements with P-polarized light incident at Brewster's angle is proposed. Additionally, appendix 2 describes a computer program I created to perform the calculations necessary for an accurate deduction of film thickness, optical properties and band strengths from reflectance spectra in general.
590 $a School code: 0246.
650 4 $a Physics, Condensed Matter. $3 1018743
650 4 $a Chemistry, Radiation. $3 1017804
690 $a 0611
690 $a 0754
710 2 0 $a University of Virginia. $3 645578
773 0 $t Dissertation Abstracts International $g 68-02B.
790 1 0 $a Baragiola, Raul, $e advisor
790 $a 0246
791 $a Ph.D.
792 $a 2007
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3251385