Experimental technique used in study of damage mechanism to semiconductor pigments exposed to ultraviolet radiation can be adapted for investigations of surface chemistry and may be used analytically to determine contamination

Gilligan, J. E.

Zerlaut, G. A.

English

NASA Technical Reports Server

July 1972	 B72-10336 
•	 NASA TECH BRIEF 
Marshall Space Flight Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Study of In-Situ Degradation of Thermal Control Surfaces 
A study has been made of the damage mechanism 
to semiconductor pigments exposed to ultraviolet radia-
tion. The experimental technique used in this study is 
of broad interest for two reasons: it may be more 
widely used for investigations of surface chemistry, and 
it may be used analytically to determine contamination. 
The materials investigated were binderless films of 
zinc oxide (ZnO), rutile titania (Ti0 2 ), and zinc ortho-
titanate (Zn 2 TiO4 ). Each of these was exposed to ultra-
violet radiation in a vacuum, causing changes in the 
reflective properties of the pigment. Since it was already 
known that damage to the pigments could be "bleached 
out" by air, test gases (02 , CO 2 , and CO) were added in 
definite increments. This made it possible to study the 
reversal of the damage and draw conclusions about both 
the bleaching and the damaging of the pigments. 
At each stage of the experiment, reflective spectra 
(from 0.325 jm to 2.6 pm) were taken in situ, to 
determine how gas pressure affected adsorption. The 
ZnU and the Zn 2 TiO4 exhibited a square root depend-
ence on oxygen pressure, suggesting monatomic oxygen 
adsorption and desorption. Ultraviolet damage to Ti02
appeared to involve at least two types of defects; at 
least one of which was surface oxygen related. Carbon 
dioxide (CO 2 ) did not seem to be involved in any of the 
surface reactions, but evidence suggested CO may react 
with adsorped or lattice oxygen to form CO2. 
Note: 
Additional information may be obtained from: 
Technology Utilization Officer 
Marshall Space Flight Center 
Code A&TS-TU 
Huntsville, Alabama 35812 
Reference: B72-10336 
Patent status: 
No patent action is contemplated by NASA. 
Source: J. E. Gilligan and G. A. Zerlaut of

lIT Research Institute

under contract to

Marshall Space Flight Center

(MFS-20892) 
Category 04 
This documentwas prepared underthe sponsorship of the National
	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	 will be free from privately owned rights.
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Study of in-situ degradation of thermal control surfaces

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