I Q~DfOnT r'nCUMENTATION PAGE I AD A263 130 - dtic. · PDF filestructure of surfaces. 8 In...
Transcript of I Q~DfOnT r'nCUMENTATION PAGE I AD A263 130 - dtic. · PDF filestructure of surfaces. 8 In...
"* �I Q~DfOnT r'nCUMENTATION PAGE I ,j. ,I
AD A263 130 .... .. . * ....... ..[..19 March 1993 Technical
4. IIILt ANLJ luoitiuc5 ~t4fG .Ash
Scanning Probe Lithography. 1. Scanning Tunneling Microscope- N(XX14-91 91-Induced Lithography of Self-Assembled n-Alkancthiol MonolayerResists
6. AUTHOR($)
Claudia B. Ross, Li Sun, andRichard M. Crooks
PERFORMING ORGANIZAT1ON NAME(S) AND ALUUMSS[ES) i PIW{kf ONtANt,.A ft
Department of Chemistry 5University of New Mexico
P% Albuquerque, NM 87131
00 *SPONSORING,&MONITORING AGENCY NAME($) ANU DOE I
0 ~ ~~Office of Naval ResearchCI GN A1,01funt
800 North Quincy StreetArlington, VA 22217-5000
11. SUPPLEMENTARY NOTES
Prepared for Publication in Langmuir 93 4 (, - )
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.13. ABSTRACT (Mjxtmum 200 w0 CIs)
The tip of a scanning tunneling microscope was used to fabricate geometrically well-defined
structures within organized, self-assembled monolayer resists that have critical dimensions ranging
from 60 nm to 5 pim. To achieve nanometer-scale lithography, a Au( Il1) substrate was coated
with a self-assembled monolayer of HS(CH2)17CH3. which functions as an ultrathin (-2.5 nm)
resist, and then the resist was etched by an STM tiq. This treatment results in window-like features
that penetrate the organic monolayer. Nanolithographically defined features have been
characterized by scanning tunneling microscopy, scanning electron microscopy, and
electrochemical methods. For example, since mass and electron transfer to the conductive Au
substrate are blocked by the monolayer everywhere except in the STM-etched regions, the
windows serve as ultramicroelectrodes. The limiting current that results from radial diffusion of a
bulk-phase redox species to the etched window is in close agereement with that predicted bv.theorvy14. SUBJECT TERMS 15. NUMBER OF PAGES
16. PRICE CODE
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Unclassified Unclassified UnclassifiedNSN 750-0. -280.5500o Standard form 295 (Rev d 89)
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Technical Report No. 5
Scanning Probe Lithography. I. Scanning Tunneling Microscope- idu'cd Lithography ofSelf-Assembled n-Alkanethiol Monolayer Resists
by
Claudia B. Ross, Li Sun, and Richard M. Crooks
Prepared for Publication 41..
in
Langmuir
Department of Chemistry
University of New MexicoAlbuquerque, NM 87131 D t
March 19. 1993
Reproduction in whole or in part is permitted for any purpose of the United States Government.
This document has been approved for public release and sale;its distribution is unlimited.
Technical Report 5,
Scanning Probe Lithography. 1. Scanning Tunneling
Microscope-Induced Lithography of Self-Assembled n-
Alkanethiol Monolayer Resists
Claudia B. Ross, Li Sun, and Richard M. Crooks*
Prepared for publication in Langmuir
The tip of a scanning tunneling microscope was used to
fabricate geometrically well-defined structures within organized.
self-assembled monolayer resists that have critical dimensions
ranging from 60 nm to 5 tm. To achieve nanometer-scale
lithography, a Au(lll) substrate was coated with a self-asspmbled
monolayer of HS(CH2 )1 TCH 3 , which functions as an ultrathin (-2.5
nm) resist, and then the resist was etched by an STM tip. This
treatment results in window-like features that penetrate the
organic monolayer. Nanolithographically defined features have
been characterized by scanning tunneling microscopy, scanning
electron microscopy, and electrochemical methods. For example,
since mass and electron transfer to the conductive Au substrate
are blocked by the monolayer everywhere except in the STM-etched
regions, the windows serve as ultramicroelectrodes. The limiting
current that results from radial diffusion of a bulk-phase redox
species to the etched window is in close agreement with that
predicted by theory.
The tip of a scanninq ýuntI,, JVt
fabricare geometrically "at-' I ý -At , f
self -assembled monolayer, r e , ..
ranging from 60 nm to 5 m.
lithography, a Au(wl!! b .,
monolayer of HS(CH 2ý ) j17CH 3 . which f'r, C t
nfn) resist, and then 'he r. . ' b L #..
treatment results in ;i'dow -1 .u," 1 o
organic monolayer. Na h . , Ly ,t,0: .Z j P. I ,
been characterized by scar, ncjng u 'rOe ;
electron microscopy, and e I ec r hemi\d :n I re
since mass and electron transfer to the onJ' u ' ....e r a..
are blocked by the monolaver everywhere ex..p...' in..
regions, the windows serve as uerami .... .. nq-
current that results from radial diffusion of a bulk-phase redo:x
species to the etched window is in close agreement with that
predicted by theory.
-2-
we wish to report t e. f rz~ --x A!fp Keso s
induced lithography of orginized' .3y.
experiment, resists cn ) of , 1y•s 1 ,3-M', 1%-e
alkanethiols which, wh,-i .A, :,
approximately 2.5 nm-thick barrl t :r to 1' ss1 t•d :?'j .i
transfer.2- 4 When a scanning tunneling , 4
positioned near the Au substr7te and t okste •e <it t'ý2c,
it induces desorption of the monolayer resis:
by STM, electrochemical methods, aind scannin.j eiect m ,ry
confirm that this technique is usefu. for flib-catn
geometrically well-defined, nanoimete -.sca a Stt e h UU
ultramicroelectrodes.
Most lithographic processes rely on light-induc r
transformations of organic polymers for fabrication micrlo'-
scale surface features. Present commercial photolithographic
processes are wavelength-limited to about 0.5 pm critical
dimensions, 5 but the development of new technologies that can
reduce this limit to 0.1 - 0.2 pm is essential for high--density,
high-speed microelectronic applications. The present sLate-of-
the-art for lithographically-defined surface features is quantum
dot cylinders with diameters of about 100 nm and thicknesses
around 10 nm. 6 The thickness is limited by the quaity of
iuecular beam epitaxy-deposited thin films, and the lateral
dimenizion is defined by the rebuLucion of electron beam
lithography. In principle, electron beam lithography should only
-3-
be limited by the wavelencgh ot . ,. *n .2 ,,., ;.. .J..--. ::.
however, as a result D) torw, scirt•.: ':-
resist and backscattering tr-m the fu-ra 1 -,:1" ,'-1,u T w
critical dimensions less than 101 .1 -ao Lt- I t 11,.
Because of the physical -, . •
feel it is desirabie t .v,..)- . ::.-x,-
fabricating structures wih cu r.: eis i: . :,,.
200 nm.
Scanning probe devi ce%-e r i: s deeope Jy L :%g ,
in 1982," and since that time have been "-:u p! z:arl 'y a o
obtaining topographical and electronic surface maps. Hcwever,
they can also be used to directly modify the cheph-ca or p}hsI
structure of surfaces. 8 In this paper, we present -he first
example of deliberate STI etching of an organic monolayer reslst.
to produce well-defined features with critical dimensions as sma~l
as 60 nm.9 Since it has been clearly demonstrated that
interpretation of STM images is sometimes ambiguous0 i0 we also
provide an independent electrochemical analysis of some of the
larger lithographically-defined features.
EXPERIMENTTAL SECTION
Substrate Preparation. A 0.25 mm-diameter Au wire (99.998%) was
cleaned by dipping in freshly prepared "piranha solution" (3:1
conc. H2 SO 4 -30% H20 2 , Caution: piranha solution reacts violently
with organic compounds, and it should not be stored in closed
-4-
containers). Au(lll) surfac s ..- . p sv . :'
in a H2 /0 2 flame under N2 , and t.hen an:, .::
the flame. 1 1 - 1 3 This treatment •esults 'n uppco×.: tKt , :f-
diameter spheres that contain j few Auli1` facets,.
The facets are typically e!lipticail, with of lon1 ,"iX" of a<bUt Y,
pm, and are composed of atomically flat terrIce.z ,b run
wide. The Au balls were cleanej again in r:
then rinsed with ethanol. To facilitate ecectrochcaIc
experiments, the entir e bal,; excec• !in nf s
Au(lll) facet, was covered with silicone ruhbbh-r uDo-Qsrnnin
Catalog No. 698). Prior to monolayer adsorption, the exposed
facet was usually polished electrochemically in an aqueous 0.1 M
HClO4 /5x10- 5 M HCI solution: this process eliminates adsonrbed
organic material from the Au surface and tends to reduce the
number of Au surface defects. 1 3 , 14 Cyclic volturnmetry co firmed
the presence of a clean Au(ll1) surface. The freshly prepared
surface was immersed in a 1 mM ethanolic solution of
octadecylmercaptan, HS(CH2 )1 7 CH 3 , for 24 h, removed, rinsed, and
then attached to a home-built STM-substrate holder for subsequent
etching and analysis.
Scanning Tunneling Microscope Etching and Imaging. A Nanoscope iI
STM (Digital Instruments, Santa Barbara, CA) was used for all ST,7
experiments. Images were obtained using a bias voltage of +300 mV
and tip currents in the range 0.10 to 0.11 nA (scan rate = 1.34
Hz). Positive bias voltages indicate that electrons tunnel from
the STM tip to the Au substrate. Tips were mechanically cut from
--5--
l b| Cth ngC~ l la
Pt /Ir (80 /2 0% ) w i r-e . T h e e- t c h Ing C, 0 UI li 1 , ....... ..... .
of the nanolithographicaaly-def med eae,, r, .md ý , e... _e_
discussed in the text. The S,!M Z-piezo was ca lbt:ttd hy
measuring several independently prepared Au2•1.. ) :....... c'. stet
edges and correlating the mean experimental•. value rotl..
theoretical Au(1lll interlayer spacinq of 0.235 -um.
Electrochemistry. Electrochemical experimueýnts we car'•ed out
a single-compartment, three-electode gass cell c..-... ,ai'ng a
Ag/AgCI, KCI(sat'd) reference electrode and a Pt co nter
electrode. Cyclic voltammograms were obtained in purifred (Mi.i!-
Q, Millipore), deoxygenated aqueous solutions ccn '~ing of 5
Ru(NH3)6 3 + and 0.1 M KCI.
RESULTS AND DISCUSSICN
STM images of a stepped Au(lll) surface covered with a single
monolayer of HS(CH2) 1 7CH 3 before and after intentional probe
etching are shown in Figure 1. The top 400 x 400 nm image was
Figure 1
obtained with a +300 mV bias voltage and a tunneling current of
0.10 nA. The Au surface contains primarily 100-200-nm-wide
atomically flat terraces separated by monoatomic steps. Small
circular defect structures, typically 5 nm in diameter, always
-6-
appear homogeneously distributed within the - H$xH-){O]
monolayer.9b0iA We are studying these sctures, Z<. ut .
present time we are uncertain of thejr precie 5t:7Ct.r .
origin. Immediately after obtaninng the top Image, h,'. .- 1
x 100 nm region was scanned four times srv. tne :•a'-
conditions used to obtain the top image. High res<u n ri 1mg
of this region, which are not shown here, indicate e
defect structures shown in the top image enlarge ani e
grow together to form much larger defects as a
substrate interactions. The bottom part. of Fgre
second image of the same region after imaging the center part four
times. Three aspects of the bottom micrograph are worth noting.
First, the center-most region of the organic surface has been
etched by the STM tip. Second, there is evidence that. the organi'c
material removed from the center part of the scan has been
deposited on the left and right edges of the etched feature.
Third, the small defects surrounding the etched portion of the
surface have been enlarged somewhat even though they have only
been exposed to the tip during two scans. These data clearly
demonstrate the feasibility of using tip-substrate interactions to
create high-resolution, nanometer-scale features on surfaces.
The physical basis for STM-tip-induced lithography is not
certain at the present time, but some combination of the following
four phenomena seems likely to contribute: (1) electron-beam-
induced degradation or desorption; (2) field ionization of
molecules resident near the tip-substrate gap that are accelerated
towards the surface, thereby desorbing the resist; (3) physical
-7-
abrasion of the Au surface by the tip; A) Joue •t:nc of the
substrate, arising from current. flowing throghth- gap
resistance, and subsequent thermal desorpt~on oi the res The
fundamental problem associated with assignIcg the pxticuliar t1.
substrate interaction(s) responsible for monolayer removal ar:;
from the uncertain z-axis displacemrnnt of the tip reiarive to the
substrate during imaging. Data discussed later suggest the tip
might be 1-2 nm above the Au surface dur-ing imaging, but since S":'ý
images are a convolution of tunneling proability and topography,
this estimate is quite speculative. Morecoer, since each STM s11 n
removes some of the organic material from the surface, it is
likely that z-displacement is also a function of the number of
times the surface is scanned and, of course, the bias voltage and
tunneling current employed. Based on the data shown in Figure 1,
particularly the distribution of organic material in the bottom
image, our present hypothesis focuses on physica1 abrasion of the
surface as the dominant tip-substrate interaction responsible for
STM-induced nanolithography under the conditions employed in these
experiments.
Figure 2A shows three 60 nm x 60 nm STEI-defined features
Figure 2
confined to a single Au(lll) terrace. In contrast to the
incomplete etching of the structure shown in Figure 1, all of the
organic material appears to have been removed within these etched
regions. This results from the more vigorous etching conditions
used to fabricate the str.c.ures con nFiu
with the tip biased at +3 v and a , ,t)
rate = 31 25 Hz) followed by four scans a'
current and scan rate. The first set of scna ipn
most of the rmnnolayer resis, bt h m':,;• .
completely remove the organic, maerial trý:-.,h,
etchea features. We have been able to c r:eae q:-:we
defined structures similar to those shown in rFgue 1'
small as 25 x 25 nm, and it appears that thI- imio
is determined only by th, size of the tIp an-, . di"
resist molecules. Such structures are d "c .. ..
least several days.
Line scans corresponding to the data in pl.ur,. 2tA are
in Figure 2B. We intentionally scanned over an atomic st< as
internal calibration of topography in acquir:ng , -a .. t'. Thi
feature can be seen in line scans 1-3, and it clearly :ndzcates
that the morphology of the underlying Au substrate can be reiably
imaged through the organic monolayer: the line scans indicate that
the Au step height is 0.22 nm, which is close t toe-e O.2.4 nm
interlayer spacing of Au(lll)912
The most interesting aspect of the 1ine scans relates to the
"depth" .f the etched features. FTIR and ellipsometric data
indicate the height of HS(CH?)j-7CH3 monolayers rance from about 2.2
nm to about 2.8 nm, but the line scans shown in Figure 2B
reproducibly indicate a depth of only 0.7±0.1 nm.>-4
Electrochemical data discussed later strongly suggest., but do not
unambiguously prove, that most of the organic resist material has
-9-
been removed from the bottom of t.e etched features. :f n&he
bottoms of the pits are clean, and if thre Au it•elf Vs not to"!.
etched, the STM tip is probably within, ranher than arove, the L,
-alkanethiol monolayer during imaguing. Kim and B":! repcrt&ed rn
depth of somewhat smaller STM-induced defects to tQ I.+-. nm,
and they explained this anomalous behavior as resulting from
differences in tunneling probabilitves.9b while ou:r data support
these previous results, we do not believe it is possible to
confirm either model at the present time.
Since it has been well-established that STM images of organic
surfaces are difficult to unambiguously interpret, 0 we used
electrochemical methods to confirm the STM data. Additionally,
the data presented here clearly indicate that STM lithography is a
good means for fabricating ultramicroelectrodes. The
electrochemical experiment is illustrated in Scheme T, and the
Scheme I
details of electrode fabrication were discussed in the
experimental section.
Figure 3A is the cyclic voltammetric response to a 5 mIL
Figure 3
Ru(NH3 )6 3 ÷ solution obtained for a Au(lll) facet after masking with
silicone rubber, but prior to HSICH2 )17 CH3 modification. The data
are intermediate between those expected for linear and radial
diffusion: a consequence of the small size of the Au(lll) facet.
-10-
After monon <ayet mw.if,"a i . Fi .gu- -i j t:,.
Faradaic current is . :... " .. -
combination of Fat ±•-A.sJi 1 ;i>n .that
advent1tious defa,; a in -v no ,_n.. ,z -:. , ;:. .
and tunnelingq c:urrer.: : V h "
Ru (NH3) 6-* . T~he C<y<'l,, Vo'j•, =r ,: a:•',- tv ,_ ,,,,-: : - .: -- • . , ,•
STM tip-inducel-: etching otne4 n i:w w.
HS(CH2) 17CH3 monoiayer t"S=,:; . A .A -a..- I',!-•V . -. :;1:
such a window is Mhoiwn; in • ". • A:
Figure 4
fabricated by scanning• he u:,-f07- twi." with o !;at v.1' 01:,
V, a tunneling current -. Ic .l , an! a -- t .* M,
The sigmoidal shape of the ... v ar,-.... : ..
radial diffusion to a small , e:. . d. in ... 7.,'thin -iA- .. . .. .. ....
ultramicroelect rode. We can ':use ,:,o-; t• i-
value for the limiting vomitat- currnt .j if wr7-1- .. -,
electrode as a disk of ra-i-A" r, rather rn ars
For this experiment. n 1 i equivmoi, F = 96485 Clequ.v, D ... . X
10-6 cm 2 /s, 1 6 and C - 5 0 x l.- m-"fcmt Approximn"i;. i by
subtracting the residual current at -0.38 7 in F1g3urc,• 32 from -he
current in Figure 3C, we calculate a value of r = 3.6 Vm. We
believe the difference between this value and the ,le ob .ai nd Y,
-ii-
visual inuspec~t•. t~ f <::-4 * -" P' • ,, :.::i: :
our assurnp " ,cn . -.. - ....
main po int is L ,•: ~ "' "': : • : ,'i.. :, ° .- •L -' ,.?, : .;
d a t a c o n f i tm tr h e .t.:'K
three additrija 5 x u. ...
in the con figurir oc ':I1' . 4 . . . .
results in an array of ult.,...t
abou threet h re•e t 'me e a rqt,, •
expected the " i ' r"j ..... : ... .: ,
the four ele r..rodtu- ,.:, ' , -. ': ' I,.:.
overlap. z
A plot of £ vers.x3 iog i-; -. , .. ... . ::::
part of the voltam~rogriims shown in Fqures 3C Jnd y: y :d a
slope of 90 mY, close to the Ialue for a th:,rdo. -i:i-y
reversible one-electron tr.ns r - 2: < n, .
supports, but does not .ncim....- .. ..- nim,
most of the organic material has been removed from 7h, . -c ,
surface in the etched areas, since a signlficant :ns'].3tIncg iayer-
would further reduce the rate of electron transfer between the
electrode and Ru(NH3 ) 63 ÷ and thus dec.ease the so t
part of -he cyclic voltamrmogram. Figure 4 suqgests the presence
of some organic material wit.hin etched region, butr the
distribution is such thca the effect on the elect iochemical
response should be negligible. The three important points that
result from the data shown in Figures 3 and 4 are: (1) it is
possible to use the STM tip to nanolithographically define
-12-
electrode arrays; K> -td i< z.LK I
result in additional F~r d.ý:u t.. ..
(3) since the elec, r Pr; .... -s : :, . .: -,
material has been reAv4d :r. tLe A• . , .'; - ;
the etched fea1Aure%.
This preliminaryrert rvi.;h! :v
intentional ST-M fabricatio:r of we:!-d•,ei f,,•,,: -:". "
self-assembled monolayer resist. The es:en.i2i t•' .<t
STM images of the nanolithographically-dle ined wrds; :.r,
confirmed by companion electrochernical experients jdri .cann!r,%
electron micrographs. Combination of the three method•s:. yields
complementary information about the nature of the pat_.te.rns• , and ,
also provides a new means for studying the nature of -the t*ip
monolayer interaction. Perhaps the most important aspect of th'i
work is that the monolayer resists are sufficiently thin to permirt
electron tunneling, but sufficiently thick to effectively block
significant mass transfer and Faradaic electron transfer across
them.
At the present time, we are pursuing several aspects of the
preliminary data presented here. First, we are using low
temperature chemical vapor deposition techniques to selectively
metallize etched regions. 17 Second, we are trying to improve the
blocking quality of the monolayers so that we can construct very
well-defined ultramicroelectrodes in the size range 1-10 nm; at
-13-
the present time elecrrodie. wii! .. cr•.> . a :-:;•,:.: , Lu:.
100 nm are too leaky to be :a-u :
experiments designed to eIucidate t..h mecL<rnasm :e:.... ...• I'.2•
tip-induced lithography. PreIimi~nary results fron th£-e
experiments will be reported shorti-y.
We gratefully acknowledge the Office of Naval Reserch for full
support of this work.
-14-
REkLr El ES
1. The results discussed here have previou:siy bee% presne
orally. (a) Crooks, R. M.; Sun, L.; Thcmlas, R.;
0. Abstracts of Papers, 18th Annual Meeting ct tc14: edeia>:.
of Analytical Chemistry and Spectroscopy Societi
CA; Federation of Analytical Chemistry and Spectroscopy
Societies: Leavenworth, KS, 1991; Abstract 657. (b) Crooks, F.
M.; Ross, C. B.; Sun, L. Abstracts of Papers, 182nd Naticnal
Meeting of the Electrochemical Society, Toronto, Canada, 1992;
Abstract 629.
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Whitesides, G. M.; Nuzzo, R. G. J. Am. Chem. Soc. 1989, 111.
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-15-
Ringger, M. ; Hidber, H. R. ;hioii,
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Brumfield, J. C. ; irelrie, E. A. 1992,
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to the results described here: ) Cas'lýaa .
an STI4 tip could be used to etch .e -, u .
thin layer of Pt-confined Ti,'." Cas,"a- !,l.;
White, H. S. 31. Elec!rocnem "-c c. 1991, 4 1.
Bard demonstrated that STM imagingj of n-acika-evt.ho mno1m ,.n r .
results in lateral expansion of advenititious der:cts {Kim, Y. -
T.; Bard, A. J. Langmuir 1992, 8, 1096).
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-17-
1. STM images of a Au (lil sur face mod"eed with a rzo ýoa,
HS (CH2 ) 17CH3. (Top) First 400 x 400 nim scan. (Bottom) Second 4n
x 400 nm scan. Four scans of the center 00 x 100 nm rgon
the surface were obtained prior to recording of the bottom itao,-.
Conditions for all six scans: bias voltage = +300 mV; tunneling
current = 0.10 nA; scan rate = 1.34 Hz.
2. (A) STM image of a Au(!lll substu&te modified with a monolayer
of HS(CH2 )I7CH 3 after opening three 60 x 60 nm windows. STM
etching conditions: four scans (bias voltage = +3 V; tunneling
current = 0.11 nA; scan rate = 31.25 Hz) followed by four
additional scans (bias voltage = +300 mV; tunneling current 01.11
nA; scan rate = 31.25 Hz). (B) STM line scans through the etchpd
regions which are shown in (A) and illustrated schematically to
the right of the line scans. The vertical displacement (v.d.)
between the arrows is indicated next to each line scan.
3. Electrochemical results obtained at (A) a naked Au(lll) facet;
(B) the same facet after modification with a monolayer of
HS(CH2 ) 1 7 CH 3 ; (C) the same facet after STM fabrication of a single
5 x 5 gm ultramicroelectrode; (D) the same facet after fabricating
four 5 x 5 pm ultramicroelectrodes spaced as indicated
schematically to the left. Conditions: solution, 5 mM
Ru(NH3 ) 63 ÷/0.l M KCl; scan rate = 100 mV/s.
-18-
4. Scanning electron mincrogriph ,-) cý
definied ultramicroelectrodec.
-19--
tac6.~, "Alta;
r) a-c a.A
Line Scans Top View
SAu Step
2
3
iJ 200 300 400 nm
Figure 2/Ross et at.
Substrate Modification
n-alkaneth.-I<-monolayer
glue
STM Lithography
STM tip
Electrochemical Anayi
Scheme I -Ross et. al.
i (nA) 50
0-
A. Naked Au (111)Facet -50-
0 -100
-0.200.
B. Au (111) I i (nA) 5HS(CH 2)1 7CH 3 z.....
-0.2 0 0.ý2
I (nA) 5-
0-
C.~' One5 x5 g
windows
-15
-0.2 6 0. 1220Opm E (V) vs. Ag /AgCI
Figure 3/Ross et al.
TEC•ItCAL. REPORT DrsT•r:':IBs C:TW
office of Naval Research (2) Dr. Richtard !. W r. z(zChemistry Division, Code 1113 Naval Civil E:gleecn800 North Quincy Street LaboratoryvArlington, Virginia 22217-5000 Code L52
Port Hueneme, CA 92-43
Dr. James S. Murday (1)Chemistry Division, Code 6100 Dr. Harold H. S.inerzan (1'Naval Research Laboratory Naval Surface Warfere CenterWashington, D.C. 20375-5000 Carderock Divisic- -etac7eznt
Annapolis, MD 21402-1198
Dr. Robert Green, Director (1)Chemistry Division, Code 385 Dr. Eugene C. Fischer (1)Naval Air Weapons Center Code 2840
Weapons Division Naval Surface Warfare CenterChina Lake, CA 93555-6001 Carderock Division Detachnent
Annapolis, MD 21402-1198
Dr. Elek Lindner (1)Naval Command, Control and Ocean Defense Technical Information
Surveillance Center Center (2)RDT&E Division Building 5, Cameron StationSan Diego, CA 92152-5000 Alexandria, VA 22314
Dr. Bernard E. Douda (1)Crane DivisionNaval Surface Warfare CenterCrane, Indiana 47522-5000
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