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The doped systems of Sm3+ ion in various solutions of some organic oximes have been studied and characterized with respect to electronic spectral parameters. The parameters viz. Judd-Ofelt (T), intensity of hypersensitive band, bonding parameters (b½, δ% &η) for doped in solution of organic oximes have been studied. The study provides useful information about interelectronic repulsion and spin interaction involved in metal-liand bond.

In the present study six organic oximes viz. acetoxime (A), acetophenoneoxime (B), bcnzophenoneoxime(C). diacetylmonooxime (D), cyclooctanoneoxime (E) and camphoreoxime (F) have been used as ligands. The solution of each ligand was prepared in 60% aqueous ethanol solution (v/v) and a constant volume of SmCI3.6H20 salt solution (w/v) has been added to this solution. Sm 3+ ion has been doped in solutions of these oximes separately in the metal ligand ratio of 1:1 and 1:2. For these doped systems, we have observed six peaks in the visible region, these are due to 4 D 3/2 , 6 P 7/2 , 6 P 3/2 , 4 P 5/2 , 4 I 13/2 and 4 M 15/2 levels. The transition 6 H 5/2 → 6 P 7/2 is hypersensitive transition.

Electronic spectral studies of lanthanoide ion complexes with reference to Judd-Ofelt parameters have been found to have due significance.

Here ‘M :  La’ and  ‘M : Lb’ represents metal to ligand ratio 1:2 and 1:1 respectively in the tables.
Spectral intensity parameters:
The computed values of oscillator strength (P_obs and P_cal) of various bands for Sm³⁺-doped systems have been tabulated in table-1 and table-2.The observed values of oscillator strength for ⁶P_7/2 band, which represents hypersensitive transition, varies from 6.959 ×10^-6 to 9.038 ×10^-6 .
Trend with respect to ⁶P_7/2  level is Da > Fa > Aa > Ca > Ea > Db > Cb > Ba > Bb > Eb > Ab > Fb.
The r.m.s. deviation between P_obs and P_cal varies from 5.686x10^-7to 1.0908x10^-6.The low value of r.m.s. deviation proved validity of Judd-Ofelt theory. 
The Judd-Ofelt parameters (T₂ ,T₄ and T₆) for Sm³⁺ doped systems have been tabulated in table-3. 
The values of T_2, T₄ and T₆ are positive for present systems. The values of T₂ varies from  9.41x10^-6 to 1.13x10⁵. The values of T₄ varies from 1.98 x10^-9 to 2.53 x10^-9. The values of T₆ varies from 3.35x10^-9 to 4.48 x10^-9.  The values  of T₄ / T₆ varies from 0.5410 to 0.6590. The values of T₄ / T₂ varies from 2.03x10^-4 to 2.46x10^-4.
The general sequence in the value of T_2, T₄ and T₆ is
 T₂  >  T₆  >  T₄
On the basis of  T₄/T₆  values, the doped Sm³⁺ ion systems have been classified in the following CLASSES:- 
(1) CLASS-1 : T₄/T₆  values varying in between 0.5400 to 0.5700. The  ligands were Aa, Ab, Da & Fa.   
(2) CLASS-2 : T₄/T₆  values varying in between 0.5710 to 0.5900.The  ligands were   Ba, Bb,  Ea & Eb.  
(3) CLASS-3 : T₄/T₆  values varying in between 0.6000 to 0.6600.The ligands were Ca, Cb, Db & Fb.
These three  CLASSES (1,2and3)  reveal  that on  changing  the  metal  to  ligand  ratio  for ligands L6, symmetry  around   the cation   or  symmetry  of  stereo environment  around the doped  Sm³⁺ ion changes. 
Nephelauxetic ratio (β) and bonding parameter (b^½, δ% &η):-
The values of nephelauxetic ratio (β) and various bonding parameters for Sm³⁺ doped systems have been tabulated in Table-4. The value of nephelauxetic ratio (β), for Sm³⁺-doped system varies from 0.99396 to 0.99874. Since the value of β is less than just one for all the systems hence presence of  very weak covalent character in metal-ligand linkage is expected.
The value of bonding parameter (b^½) varies from 0.025 to 0.0549. The value of b^1/2 represents the mixing of metal ion 4 f orbitals with the ligand orbitals. The positive value of bonding parameter indicates covalent character in metal-ligand bond. The value of Sinha’s covalency  parameter (δ%) varies from 0.1252 % to 0.6067 % and value of covalency angular overlap parameter (η) varies from 6.26x10^-4 to3.03x10^-3.Sm³⁺ systems surrounded by benzophenoneoxime having metal-ligand ratio1:1 have the highest covalent character in metal- ligand bond in the present study.
Hypersensitive transition and validity of peacock’s relation ( p a`n t<sub>6</sub> )-
In Sm<sup>3+</sup> ion, the transition <sup>6</sup>H<sub>5/2</sub> → <sup>6</sup>P<sub>7/2,</sub> is regarded as hypersensitive transition. For  hypersensitive  transition, oscillator strength (P) is directly proportional  to `nT₆, this linear correlation has been proposed by R.D.Peacock¹⁵. Hence proportionality constant ( K = P /`n T₆) should be constant for the present systems. The value of  proportionality constant K, for Sm³⁺  doped systems varies from 0.0745to 0.0810. All ligands, except Ligand ‘Ba’ i.e. acetophenoneoxime with metal ligand ratio 1:2, exhibit   almost constancy in the value of K.
Materials and method-
All the chemicals and the solvent used were of analytical grade. SmCI₃.6H₂0 having 99.9% purity was supplied by Indian Rare Earths Ltd. The ligands were dissolved to prepare 0.32 M and 0.16 M solutions in 60% aqueous ethanol (v/v) at room temperature (36 °C). Equal volume (10 ml) of each of these 0.32 M and 0.16 M ligand solution was added in 10 ml solution of 0.16M SmCI₃.6H₂0 to get systems of having metal to ligand ratio I : 2 and I : I respectively. Solution spectra of these twelve systems were recorded by using standard spectrophotometer ( Biomate UV-Visible spectro-photometer v7.07) in the range of 350 to 600 nm.

Table-1: Computed values of oscillator strength for Sm ³⁺ doped systems-


Table-2: Computed values of oscillator strength parameters for Sm ³⁺ doped systems:- 

Table-3: Computed values of Judd-Ofelt parameters for Sm ³⁺ doped systems-
 

Table-4: Computed values of bonding  parameters for Sm ³⁺ doped systems-

The calculation of parameters viz. Oscillator strength (P), Judd-Ofelt (T) bonding parameters (b½, δ% &η) have been computed by the programme developed by earlier workers 13- 16. The computed values of oscillator strength, Judd-Ofelt parameter , bonding parameters and nephelauxetic ratio have been tabulated (Tables 1-4).

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