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Renewing investigation of luminescence spectra of CdCl2:Mn2+
Journal of Luminescence 31 & 32(1984)287-289 North-Holland. Amsterdam
287
2~
RENEWING INVESTIGATION OF LUMINESCENCE SPECTRA OF CdCl
2:Mn
Xia SHANGDA and Chen SHAOJIANG Department of Physics, China University of Science and Technology, Hefei, Anhui , China Including the D~ddistortion and the ph9non contribution, the spectra of CdCl 2:Mn~published by B. Ghosh et al.’ have been studied again. A new assignment and crystal—field fitting calculation using V. Tanabes tensor operator method have been done and a good result obtained. INTRODUCTION 3 studied the spectra of CdCl 2~(Mn = 0.1%). Trutiaetet al.1 al. measured the emission and excitation 2:Mn And Inin 1975 1980Ath B. Ghosh spectra of CdCl 2~ (Mn = 1%) again. B. Ghosh et al. also assigned the spectra and made 2~Mn a crystal—field fitting calculation under cubic crystal—field approximation. In our opinion, it is valuable to renew the following aspects of previous work1: 1.1. The six peaks between 26660 cm~and 27390 cm’~ do not look as excitonmagneton and phonon sideband to us, for the ion Cd2+ and Cl’~1 have no magnetic momentum and the concentration of Mn2+ is too low for the interchange interaction to occur. And the low intensities of the spectra also support this suspicion. 1.2. The three peaks at 23670 cm’~’, 23860 cm~ and 23980 cm~attributed to 4E(G)
+
1.3.
4A 1(G) were not understood exactly. The odd-parity phonons were not considered in their fitting calcula-
tions. But they must have contributed to ehe electric dipole transitions for the parity conservation. 1.4. No trigonal distortion (D3d) evidence was obtained from the spectra, despite the evidence in spin resonance data. questionable.
This conclusion is also
2. THE MAIN POINTS OF THE NEW ASSIGNMENT 2.1. There have been D3d distortion evidences in the and it is D3d 4E(G) and spectra 4A that removes the accident degeneration1 between 1(G) in and 23860 cm~. The large °hsymetry, splitting givingcm~) the between two energy 23670 cm (190 thenlevels can not be caused by the spin—orbit interaction which has zero diagonal matrix elements in all the states 4E(G) and 4A(G). In addition, the peaks at 23670 cm~and 23860 cm~ are assigned as no-phonon magnetic 0O22—2313/84/$03.OO© Elsevier Science Publishers By. (North-Holland Physics Publishing Division)
S7angda, C Sliao/iang / Lui inc~cr,uc~pec1ra nf (dC 12.
288
6A
transition
4E(G) and 6A
4A
1(G) respectively, for their shapes are sharp and their positions remain approximately unchanged when the temperature changes. 5,6 2.2. All the electrical dipole transition peaks are odd—parity phonon sidebands. The phonon spectrum data are taken from the ones of CdC12 and 7’8 MnC12, for bothexample, of them the havepeak approximately the issame infrared asandone-phonon Raman spectra. Then, at 23980 cm”1 considered sideband corresponding to 6A
4A 1
1(G). 4T 2.3. There are the largest spin-Orbit splitting in the 1 and 27390 cm1 have beenmultiplet assigned as2(D). phonon So the sixwhich peaksis between sideband based on26660 the Dcm 4T 3d and spin-orbit splitting of 2(D). 2.4. According to reference 5, the broad peak at 18760 cm’~ should be the 6A 4T 4T multi-phonon sideband corresponding to 1 -~ 1(G), 6A since different slope in the Orgel diagram compared to 1. 3. CRYSTAL-FIELD FITTING CALCULATION We chose the threefold axis as 7—axis.
1 has a very
The following calculations have been 2 tensor
carried out in °hcrystal—field representation using Y. Tanabe s operator method.
3.1. The following H~has been diagonalized in three matrices 4E(8x8), Hamiltonian 4A 4A of multiplets 1(4x4) and 2(4x4): = H + H + H(0 ) + H(D ) 0 e Trees h 3d where H(D3d) = V(T2) which is part of the general trigonal distortion Hamiltonian V(A2) + V(T1) + V(T2). We have introduced the one-electron
H
double barred matrix elements as D3d parameters:
=
S
Kdt2iv(t2)Udr
The matrix elements of H Trees have15Lbeen taken from 2reference 9. the of references should take 3.2. The spin-orbit Hamiltonian following form when the threefold axis is 7-axis: S
v 00 (1T1)
=
v1~(lT1)- v1(lT1)
and the spin—orbit parameter <~drIrstV~dr>/3 5 ion located in D Only 2(D) 10hasSo larger splitting for (3d) the multiplet 4T 3d we havespin-orbit simply diagonalized HSL the within crystal-field. 2(D), that is only within the matrices of F4(4x4) and F56(2x2). =
4T
-i~drUstfl~dr>/3
=
i/2
2~
X. Shangda, C Shaojiang/ Luminescence spectra of CdC1
289
2.Mn
4. THE RESULTS OF THE FITTING CALCULATION. All the results are shown in Table 1.
Obviously, the results are very good
by noticing that the peaks corresponding to 4T in the broad bands and the discriminability
4E and 4T
4E are buried
2(E)range (> 30000 in1(E) high frequency
cm~) is lower.
Table 1.
The Comparison of Fitting Calculation Results (units:
This paper~ ~
__________
States
=
300
B =776. a_=76. Level
O~
B
(T
heo.
~ ero-_phonon
cm’~).
C =2900, D~=642, ____________ Refervecel . B =767, C r=26%o. ~=670 L eve1 ( ~ Level
2333
______________
pIwlsurss
80
°K 300 8K (T heo.)
‘T
0 4Ts(G)
— 1(C) ._~.L._ A~ ‘T~G) 4A 1
18808 18055 22034 22540 23670 23860
—
~A 1(G)
A,
+705
______________
+189(E,,.)
18760 22223
_____________
—
‘T,(P)
— —
18910
18683
22220
22500
22275
0
23670
23670 23690 23860 23870 23980 26660 26840 5~o50 27020 27100
23855
0
23860
(23860) +1e2(E,~ ) 24022 •A,(265J2)r4 1 26512 + 162(E~) 26674 4E26832r~+r~ F4 26690 + 162(Es) 26861 F, 26788 + 162(},~) 269~r ~ F~ 26876 + 162(E,~) 27038 F. 26965 + 162(E,.) 27127 27130 26965 +189(F.,d+23A(A )~j~88 27390 ‘8 28053 +162(Eu) 28215 28170
E ‘A. ‘A2 E
‘AyF) ‘hF) ‘f,(f)
18760
_______
—
~~55
_______
—h-— ~
30316 30453 38287 38776 ______________________
41586 41092
‘E
+0
30316
30300
+ 26772
30120
______
38532 38938 41300 ______
38800 41300 -~
39200
38317 ‘A.tF) 39015 ‘l’i(F) 41285 ‘T,(F’) ______
1)
B. Ghosh et al., Phys. Stat. Sol. (B) 102 (1980) K89.
2)
V. Tanabe et al., J. Phys. Soc. Japan 9 (1954) 753; 13 (1958) 394.
3)
Ath Trutia et al., Phys. Stat. Sol. (B) 70 (1975) K19.
4)
H. G. Hoeve et al., Phys. Rev. 167 (1968) 245.
5)
J. Gerguson et al
6)
L. L. Lohr et al., J. Chem. Phys. 49 (1968) 3516.
7)
A. Anderson et al., Spectrosc. Lett. 14(2) (1981) 105.
8)
D. J. Lockwood, J. Opt. Soc. Amer. 63 (1973) 374.
9)
A. K. Mehra, J. Chem. Phys. 48 (1968) 4384.
10)
Mol
.
Phys. 28 (1974) 879.
J. C. Flempel et al., J. Chem.
‘T~(D)
28160 ~ 30526
REFERENCES
. ,
4E(G)
_______
2.aizQ...
____________
+245(A.,,) + 162(E~) 208(A,~) _____________ ____________ +
‘T~)
Phys. 64 (1976) 4314.
—
287
2~
RENEWING INVESTIGATION OF LUMINESCENCE SPECTRA OF CdCl
2:Mn
Xia SHANGDA and Chen SHAOJIANG Department of Physics, China University of Science and Technology, Hefei, Anhui , China Including the D~ddistortion and the ph9non contribution, the spectra of CdCl 2:Mn~published by B. Ghosh et al.’ have been studied again. A new assignment and crystal—field fitting calculation using V. Tanabes tensor operator method have been done and a good result obtained. INTRODUCTION 3 studied the spectra of CdCl 2~(Mn = 0.1%). Trutiaetet al.1 al. measured the emission and excitation 2:Mn And Inin 1975 1980Ath B. Ghosh spectra of CdCl 2~ (Mn = 1%) again. B. Ghosh et al. also assigned the spectra and made 2~Mn a crystal—field fitting calculation under cubic crystal—field approximation. In our opinion, it is valuable to renew the following aspects of previous work1: 1.1. The six peaks between 26660 cm~and 27390 cm’~ do not look as excitonmagneton and phonon sideband to us, for the ion Cd2+ and Cl’~1 have no magnetic momentum and the concentration of Mn2+ is too low for the interchange interaction to occur. And the low intensities of the spectra also support this suspicion. 1.2. The three peaks at 23670 cm’~’, 23860 cm~ and 23980 cm~attributed to 4E(G)
+
1.3.
4A 1(G) were not understood exactly. The odd-parity phonons were not considered in their fitting calcula-
tions. But they must have contributed to ehe electric dipole transitions for the parity conservation. 1.4. No trigonal distortion (D3d) evidence was obtained from the spectra, despite the evidence in spin resonance data. questionable.
This conclusion is also
2. THE MAIN POINTS OF THE NEW ASSIGNMENT 2.1. There have been D3d distortion evidences in the and it is D3d 4E(G) and spectra 4A that removes the accident degeneration1 between 1(G) in and 23860 cm~. The large °hsymetry, splitting givingcm~) the between two energy 23670 cm (190 thenlevels can not be caused by the spin—orbit interaction which has zero diagonal matrix elements in all the states 4E(G) and 4A(G). In addition, the peaks at 23670 cm~and 23860 cm~ are assigned as no-phonon magnetic 0O22—2313/84/$03.OO© Elsevier Science Publishers By. (North-Holland Physics Publishing Division)
S7angda, C Sliao/iang / Lui inc~cr,uc~pec1ra nf (dC 12.
288
6A
transition
4E(G) and 6A
4A
1(G) respectively, for their shapes are sharp and their positions remain approximately unchanged when the temperature changes. 5,6 2.2. All the electrical dipole transition peaks are odd—parity phonon sidebands. The phonon spectrum data are taken from the ones of CdC12 and 7’8 MnC12, for bothexample, of them the havepeak approximately the issame infrared asandone-phonon Raman spectra. Then, at 23980 cm”1 considered sideband corresponding to 6A
4A 1
1(G). 4T 2.3. There are the largest spin-Orbit splitting in the 1 and 27390 cm1 have beenmultiplet assigned as2(D). phonon So the sixwhich peaksis between sideband based on26660 the Dcm 4T 3d and spin-orbit splitting of 2(D). 2.4. According to reference 5, the broad peak at 18760 cm’~ should be the 6A 4T 4T multi-phonon sideband corresponding to 1 -~ 1(G), 6A since different slope in the Orgel diagram compared to 1. 3. CRYSTAL-FIELD FITTING CALCULATION We chose the threefold axis as 7—axis.
1 has a very
The following calculations have been 2 tensor
carried out in °hcrystal—field representation using Y. Tanabe s operator method.
3.1. The following H~has been diagonalized in three matrices 4E(8x8), Hamiltonian 4A 4A of multiplets 1(4x4) and 2(4x4): = H + H + H(0 ) + H(D ) 0 e Trees h 3d where H(D3d) = V(T2) which is part of the general trigonal distortion Hamiltonian V(A2) + V(T1) + V(T2). We have introduced the one-electron
H
double barred matrix elements as D3d parameters:
=
S
Kdt2iv(t2)Udr
The matrix elements of H Trees have15Lbeen taken from 2reference 9. the of references should take 3.2. The spin-orbit Hamiltonian following form when the threefold axis is 7-axis: S
v 00 (1T1)
=
v1~(lT1)- v1(lT1)
and the spin—orbit parameter <~drIrstV~dr>/3 5 ion located in D Only 2(D) 10hasSo larger splitting for (3d) the multiplet 4T 3d we havespin-orbit simply diagonalized HSL the within crystal-field. 2(D), that is only within the matrices of F4(4x4) and F56(2x2). =
4T
-i~drUstfl~dr>/3
=
i/2
2~
X. Shangda, C Shaojiang/ Luminescence spectra of CdC1
289
2.Mn
4. THE RESULTS OF THE FITTING CALCULATION. All the results are shown in Table 1.
Obviously, the results are very good
by noticing that the peaks corresponding to 4T in the broad bands and the discriminability
4E and 4T
4E are buried
2(E)range (> 30000 in1(E) high frequency
cm~) is lower.
Table 1.
The Comparison of Fitting Calculation Results (units:
This paper~ ~
__________
States
=
300
B =776. a_=76. Level
O~
B
(T
heo.
~ ero-_phonon
cm’~).
C =2900, D~=642, ____________ Refervecel . B =767, C r=26%o. ~=670 L eve1 ( ~ Level
2333
______________
pIwlsurss
80
°K 300 8K (T heo.)
‘T
0 4Ts(G)
— 1(C) ._~.L._ A~ ‘T~G) 4A 1
18808 18055 22034 22540 23670 23860
—
~A 1(G)
A,
+705
______________
+189(E,,.)
18760 22223
_____________
—
‘T,(P)
— —
18910
18683
22220
22500
22275
0
23670
23670 23690 23860 23870 23980 26660 26840 5~o50 27020 27100
23855
0
23860
(23860) +1e2(E,~ ) 24022 •A,(265J2)r4 1 26512 + 162(E~) 26674 4E26832r~+r~ F4 26690 + 162(Es) 26861 F, 26788 + 162(},~) 269~r ~ F~ 26876 + 162(E,~) 27038 F. 26965 + 162(E,.) 27127 27130 26965 +189(F.,d+23A(A )~j~88 27390 ‘8 28053 +162(Eu) 28215 28170
E ‘A. ‘A2 E
‘AyF) ‘hF) ‘f,(f)
18760
_______
—
~~55
_______
—h-— ~
30316 30453 38287 38776 ______________________
41586 41092
‘E
+0
30316
30300
+ 26772
30120
______
38532 38938 41300 ______
38800 41300 -~
39200
38317 ‘A.tF) 39015 ‘l’i(F) 41285 ‘T,(F’) ______
1)
B. Ghosh et al., Phys. Stat. Sol. (B) 102 (1980) K89.
2)
V. Tanabe et al., J. Phys. Soc. Japan 9 (1954) 753; 13 (1958) 394.
3)
Ath Trutia et al., Phys. Stat. Sol. (B) 70 (1975) K19.
4)
H. G. Hoeve et al., Phys. Rev. 167 (1968) 245.
5)
J. Gerguson et al
6)
L. L. Lohr et al., J. Chem. Phys. 49 (1968) 3516.
7)
A. Anderson et al., Spectrosc. Lett. 14(2) (1981) 105.
8)
D. J. Lockwood, J. Opt. Soc. Amer. 63 (1973) 374.
9)
A. K. Mehra, J. Chem. Phys. 48 (1968) 4384.
10)
Mol
.
Phys. 28 (1974) 879.
J. C. Flempel et al., J. Chem.
‘T~(D)
28160 ~ 30526
REFERENCES
. ,
4E(G)
_______
2.aizQ...
____________
+245(A.,,) + 162(E~) 208(A,~) _____________ ____________ +
‘T~)
Phys. 64 (1976) 4314.
—