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MICROCOFY RESOLUTION TEST CHART
NATIONAL BUREAU OF STANDARDS - 1963

.
(Austrnct - Internationnl Conference on Ilyperrine Internctions Detected by
Nuclcar Radiation, incific Grove, California, August 25-30, 1967)
ORNV -3251
CONF-670812-13
AUG 25 1967
ORAL - AEE = OFFIEIAL
ORN = 46=ePRSAL
Mossbauer Experiments with Nickel-61.* John C. Love and Gordon Czjzek,
LKL
Oak Ridge National Laboratory, J. J. Spijkerman and D. K. Snediker, National
Bureau of Standards. - Using "Ni Mossbauer effect, we have measured the
ratio of the magnetic moments of 62N1 nuclei in the first excited state
and the ground state: u(5/2)/u(3/2) = -(0.559 $ 0.012). Hyperfine fields
at nickel nuclei in iron (241 $ 7 kilogauss) and in a NI (85%) Cr (15%)
alloy: (1.15 kilogauss) are determined. Very approximate values for
isomer shifts of some nickel alloys, Nify, and Nio are given.
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Research sponsored in part by the U.S. Atomic Energy Commission under con-
tract with Union Carbide Corporation.
.
COM PICOS
LEGAL NOTICE
This report was prepared as an account of Government sponsored work. Neither the United
Statos, nor the Commission, nor any person acung on behalf of the Commission:
A. Makes any warranty or representation, expressed or implied, with respect to the accu-
racy, completeness, or usefulness of the information contained in this report, or that the uso
of any information, apparatus, method, or procoso disclosed in this raport may not infringo
privately owned rights; or
B. Assumes any llapilities with respect to the use of, or for damages resulting from the
use of any information, apparatus, method, or process disclosed in this report,
As used in the above, "peran acting on behall of the Commission" Includes any en-
ployee or contractor of the Commission, or employee of such contractor, to the extent that
Buch employee or contractor of the Commission, or employee of such contractor preparea,
dissominates, or provides access to, any information pursuant to his employment or contract
with the Commission, or hio employment with such contractor.
H0 93.00, MN ebé
ORNAL
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OFFICIAL
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DISTRIBUTION OF THIS DOCUMENT 15 UNGMITED
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MÖSSBAUER EXPERIMENTS WITH NICKEL-61
ORNI - AEC - OFFICIAL
· Oak Ridge National Laboratory**
Oak Ridge, Tennessee
and
***
J. J. Spijkerman and D. K. Snediker
National Bureau of Standards
Gaithersburg, Maryland
Many significant Mössbauer experiments with Ni are possible because
of the magnetic and chemical properties of nickel and its various alloys and
compounds. Although the first experiments+,2) with Ni were done seven
years ago, the literature indicates that little has been done since then.
The difficulty seems to be finding a suitable non-magnetic source. The two
possible radioactive parents, Co and ºfcu, are both short-lived and this
makes it inconvenient to do radiochemical separations after irradiation.
Mössbauer experiments with this isotope are now under way at both the
National Bureau of Standards and the Oak Ridge National Laboratory, and
we report here our preliminary results. In particular, we have made some
progress with the problem of source preparation, we have determined the
magnetic moment of the first excited state (spin 5/2) of 4N1 to a better
precision, and we have observed isomer shifts and effective hyperfine
fields H at the 62N1 nucleus in several materials.
The sources used in the experiments reported here were produced in
three ways. The NBS source is a Ni (85%) Cr (1.5%) solid solution which
18 irradiated in the bremsstrahlung beam produced by the NBS LINAC.
The sou
BRM - ATE=OFFTEIAL
ORNL - AEC - OFFICIAL
Irradiation times are typically one hour and electron energies of the order
of 100 MeV are used. A 62co source is produced by the reaction 62N1(7,0)62co.
The Odco then beta-decays (T. 10 = 99 min) to the first excited state of Ni
(spin 5/2) which then gamma-decays with a half-life of 5.3 nanoseconds to the
ground stete (spin 3/2). A short-lived (12/2 - 2.5 min) activity 16 pro-
duced in the chromium. The gamma spectrum of the olco is very clean with
a signal/noise ratio greater than ten. This source has a small residual
hyperfine field at 80°K of about 15 kilogauss estimated from the broadening
of the spectrum seen in Fig. 1, which is a Mössbauer spectrum taken with a
copper 98% - nickel 2% absorber known to be non-magnetic. Another spectrum
taken with a NiF, absorber, but with considerably fewer counts per data
point, 18 shown in Fig. 2. The line broadening, 1.45 times the minimura,
indicates a field of 12 kilogauss.
At Oak Ridge we have taken data with a source of 62.Co in a 6411 .
matrix produced by 22 MeV protons from the 86 inch cyclotron by the reac-
tion *N1 (0,4)04co, (see ref. 1). This source is, of course, nagnetic and
Fig. 3 shows a Mossbauer' spectrum taken with the same Cu-Ni (2%) absorber
used for Fig. 1, in this case, at 4.2°K.
A third possible source is the Coulomb-excitation of the ri (5)
and recently we have done an experiment at Oak Ridge using the Coulomb-
recoil-implantation-Mossbauer-effect technique using 25 MeV oxygen ions
from a tandem Van de Graaff to Couiomb excite and implant Ni nuclei
into a copper backing. The source thus produced, at 86°k, and an absorber.
of powdered N1F, in epoxy, at 78°K, yielded the data for Fig. 4. (This is
the same absorber that was used to take the data for Fig. 2). The width
of this line 1$ 1.11 times the minimum value and is consistent with the
effective thickness of the absorber, indicating a single-line source.
OBNEAEOFFICIAL
ii.
FAC Mil
BRWARE
:
Disadvantages of this method are the long irradiation periods needed (12
hours in this case) because of the small B(E2) for this transition and the
poor gamma spectrum (signal/noise ~0.6). However, impurity concentrations
of the order of parts per million can be studied with the Mössbauer effect
by this technique.
The value of the Mügnetic moment of the ground state of Ni has
been measured by NMR(5) (-0.74868 nm.) and ENDOR(6) (-0.746 nm.) experi-
ments. A value of the ratio of the excited and ground state moments had
been obtained by Wegener and Obenshain (see ref. 2) as u(5/2)/+(3/2) =
-(0.64 0.33) from purely Mössbauer results or -(0.47 + 0.08) using the
MMR value for the ground-state splitting for interpretation of their data.
In order to improve on this measurement, we have analyzed the data taken
with the 54N1.(,0) %Co magnetic source and copper-nickel absorbers with
the following nickel concentrations: 2%, 13.5%, 26.4%. For the fitting
of these data, the positions of the outer two of the twelve Lorentzien
lines were independently varied and the positions of the other lines were
then scaled accordingly, using the MMR value for the ground state split-
ting of Oni in nickel. Our result is u15/2)/u(3/2) = -(0.551 + 0.038)
where the error bar 18 only a statistical one.
An independent value of this ratio is obtained from Pitting the
spectrum shown in Fig. 5. Here the NBS NiCr source is used with an absorber
of 1.5% of Ni in iron. For the fitting of these data, six of the line
positions are independently varied and no a priori value for the ground-
state splitting is assumed. The result is u(5/2)/+(3/2) = -(0.568 $ 0.055).
The measured grour.3-state splitting of (1.62 + 0.05) mm/sec implies a value
· for the hyperfine field or H, = (211 + 7) kilogauss. This agrees with the
WR value of 235 kilogauss.'° A weighted average of all our results yields
BINE - AEE-8FFEIAŁ

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1V131310 - 33-1897.
(5/2)/u(3/2) = -(0.559 $ 0.012) and using the MMR value for u(3/2)(5) we
get for the excited state moment: (5/2) = +0.419 + 0.010 ) mm.
ORNL - AEC - OFFICIAL
ORNI - AEC - OFFICIAL
The isomer shifts observed for some of the spectra we have obtained
are listed in Table I. It is evident that they are rather small and the
values listed should be considered only as preliminary results.
We would like to thank George Lutz for many LINAC irradiations, and
Felix Obenshain for enlightening discussions and for reading the manuscript.
The interest and comments concerning our results by Horst Wegener are appre-
ciated. One of the authors (J.C.L.) would like to acknowledge travel sup-
port from the Oak Ridge Associated Universities for a trip to Gaithersburg
making this collaboration possible.
ORNL - KEC - OFFICIAL
ORNI - ABC-QFFICIAL
5
REFERCNCES
BRNE = AEE = RFFIETA!"
*Oak Ridge Graduate Fellow from Ohio State University under appointment
with Oak Ridge Associated Universities.
* Research sponsored by V.S. Atomic Energy Commission under contract with
the Union Carbide Corporation.
***
Now at General Electric, Philadelphia, Pennsylvania.
1. Felix E. Obenshain and Horst H. F. Wegener, Phys. Rev. 121, 1344 (1961.).
2. Horst 1. F. Wegener and Felix E. Obenshein, 2. Physik 163, 17 (1961).
Dietrich Seyboth, Felix E. Obenshain, and Gordon C2jzek, Phys. Rev.
Letters 24, 954 (1965).
4. Gordon Czjzek, J. L. C. Ford, Jr., John C. Love, Felix E. Obenshain,
and Horst H. F. Wegener, Phys. Rev. Letters 18, 529 (1967).
5. L. E. Drain, Phys. Letters 11, 114 (1964).
6. P. R. Locher and $. Geschwind, Phys. Rev. Letters 11, 333 (1963).
7. The value used for the ground-state splitting at 4.2°K, (28.1 + 0.1)10°
cps, was obtained by extrapolating the data of L. J. Bruner, et. al.,
Phys. Rev. 121, 83 (1961). ::
8. R. L. Streever, Li H. Bennett, R. C: •LeForce and G. F. Day, J. Appl.
Phys. 34, 1050 (1963).
ORNI - AEC - OFFICIAL
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IF

TABLE I
BNL-RE-OFFICHA
SRNU - AEE-8FFIEIAŁ
Source
Absorber
Isomer Shift
· (rom/sec.)
NiCr (15%)
FeNi (1.5;)
Nio
CuNi (20%)
CuNi (2%)
+ (0.10 $ 0.01)
+ (0.05 $ 0.02)
- (0.10 $ 0.03)
-'(0.03 $ 0.01)
+ (0.126 + 0.040)
+ (0.32 $ 0.11)
Nita
Nita
bni implanted in Cu
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FIO. 1
NBS SPECTRIJM, RUN NO..
1.010 L
NICA(150) VS CUNI (26)
L
-2
-
1.000
RELATIVE INTENSITY
.990
.
.970
.960
b
950
D O
BRNU=AEE-BFHEIAL
20
40
60
80
FIG./
100
120
140 A160 8U
ien

LILLE
ORNY- RE- OFFICIAL
• ORAL-ASE-OFFIGAR
· FIG. 2,
NBS SPÉCTRUM, NICR (159) VS NIF2
,0260 -
nu 1967
RELATIVE INTENSITY
. 0245
0240
.
.0235
.0230 H
0
20
40
60
80
100
120
240
CHERO. NUMERO
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FIG.?
BRN = 48E=B1EAL

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TRANSMISSION
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1000
- 1967.
549 ABSORBER CU-NI, DATE

109

100T .
OS 619 IN
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• OPNI - AEC - OFFICIAL
FIG. 4, NI-61 IN CU VS NIF2
64507
RELATIVE INTENSITY
-
FOEF. °
.4267
0
20
40
.
80
100
120
60
FIG. Z
160
180
140
CHANNEL NUMBER
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FIG. 5, NBS SOURCE NICR (15) VS FENI (105)
1.010!
1.005.
RELATIVE INTENSITY
ID
.990_
IN
.985
09804
0,
20
40
60
80
100
120
140
160
180
** habet cas
ORNL - AEC - OFFICIAL
CHANNEL NUMBER
, ORN! - AEC - OFFICIAL
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