Determination of Particle Size Distribution of Water-Soluble

CdTe Quantum Dots by Optical Spectroscopy

J.C.L. Sousa1, M.G. Vivas2,3, J.L. Ferrari1, C.R. Mendonca3, M.A. Schiavon*,1

1Grupo de Pesquisa em Química de Materiais (GPQM), Departamento de Ciências Naturais, Universidade

Federal de São João del-Rei, 74, 36301-160, São João del-Rei, MG, Brazil 2Instituto de Ciência e Tecnologia, Universidade Federal de Alfenas, Cidade Universitária - BR 267 Km 533,

37715-400, Poços de Caldas, MG, Brazil 3Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, 13560-970 São Carlos, SP,

Brazil

0.000 0.002 0.004 0.006 0.008 0.010 0.012 0.0140

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 L inear  F it  of  R hodamine  6G  L inear  F it  of  R hodamine  101

Integrated

 Pho

tolumines

cenc

e  Area  (a.u.)

A bs orbance  λ = 355  nm

Equation y  =  a  +  b*xAdj.  R -­‐S quare 0.9938

ValueR hodamine  6G Intercept -­‐4.68478R hodamine  6G S lope 318496.59652

Equation y  =  a  +  b*xAdj.  R -­‐S quare 0.99625

ValueR hodamine  101 Intercept -­‐59.98849

R hodamine  101 S lope 328266.14634

Figure S1. Calibration curves for the fluorescence quantum yield of rhodamine 6G (97%) in aqueous media by using rhodamine 101(100%) as reference.

Electronic Supplementary Material (ESI) for RSC Advances.This journal is © The Royal Society of Chemistry 2014

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Figure S2. Calibration curves for the fluorescence quantum yield of rhodamine 6G (97%) and CdTe-GSH (60 minutes of synthesis) in aqueous media.

 

0.000 0.002 0.004 0.006 0.008 0.010 0.012 0.014 0.016 0.0180

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 L inear  F it  R hodamine  6G  L inear  F it  C dTe-­‐G S H  60  MinutesP

hotolumines

cenc

e  Integrated

 Area  (a.u.)

A bs orbance  λ = 355 nm

Equation y  =  a  +  b*xAdj.  R -­‐S quare 0.9938

ValueR hodamine  6G Intercept -­‐4.68478R hodamine  6G S lope 318496.59652

E quation y  =  a  +  b*xAdj.  R -­‐S quare 0.99942

ValueC dTe-­‐GS H   Intercept 7.7775660  Minutes S lope 98738.85373

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Figure S3. Fluorescence spectra of CdTe QDs (30 minutes of synthesis) obtained after ex-citation at different wavelengths.

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Figure S4. Forward and backward analysis for the CdTe QDs (30 minutes of synthesis).

Figure S5. Pure component spectra obtained from the EFA-MCR method for the CdTe QDs (30 minutes of synthesis).

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4Forward and backward analysis

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QDs size dispersion program clear all; format long; %Graphic parameters COR=['b' 'g' 'r' 'c' 'm' 'y' 'k'];k=7; cor=COR(k); ft=14; aa=2.0; axy=2.0; ttitulo=11; awords=1.5; %************************************************************************ %************************************************************************ %Pathway p=path; path(p,'put the pathway'); arq_I=load('put the matrix M (n,m)'); arq_lamb=load('put the matrix W(m)'); arq_exc=load('put the excitation wavelength matrix'); arq_A=load('put the absorption spectrum data'); arq_lamp=load('put the lamp data intensity'); IF_exp= arq_I'; lamb_exp= arq_lamb'; lamb_exc=arq_exc(:)'; lamb_abs=arq_A(1,:)'; A_exp=arq_A(2,:) '; I_lamp=arq_lamp(2,:)'; lamb_lamp=arq_lamp(1,:)'; %************************************************************************ % Filter routine N=length(A_exp); N1=length(I_lamp); [m,n]=size(IF_exp); lamb_fluo_ini=lamb_exp(1); for i=1:m for j=1:n if(lamb_exc(i)>lamb_fluo_ini) if((lamb_exc(i)>=((lamb_exp(j)+2)-7)) && lamb_exc(i) <= ((lamb_exp(j)+2)+0)) M_aux(i,j)=IF_exp(i,j); else M_aux(i,j)=0.0; end end end end

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for i=1:m for j=1:n M_aux_2(i,j)=IF_exp(i,j)-M_aux(i,j); end end M_aux_2=IF_exp; %*************************************************************** % Obtaining the absorbance value corresponding to the excitation wave-length for i=1:m for j=1:N if lamb_abs(j)==lamb_exc(i) A_exp_aux(i)=A_exp(j)+0.001; end end end %Storing the lamp data lamb_lamp=round(lamb_lamp); count=0.0; AS=mean(I_lamp); for i=1:m for j=1:N1 if (lamb_lamp(j)==lamb_exc(i)) I_lamp_aux(i)=I_lamp(j); end end end I_lamb_aux=I_lamp_aux/max(I_lamp_aux); for i=1:m IF_exp_max(i)=max(IF_exp(i,:)); end % Introducing the calibration curve (diameter versus fluorescence peak) and finding the wavelength that corresponds to the fluorescence peak aux_D=0.0; for i=1:m for j=1:n if IF_exp(i,j)==IF_exp_max(i) lamb_exp_aux(i)=lamb_exp(j); end end D(i)= put the empirical equation (diameter versus fluorescence peak); end %************************************************************************

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% Introducing the calibration curve “fluorescence quantum yield versus diameter” aux_D=0.0; for i=1:m for j=1:n if IF_exp(i,j)==IF_exp_max(i) lamb_exp_aux(i)=lamb_exp(j); end end QY_f(i)= put the empirical equation (QY versus diameter);; end QY=QY_f; %************************************************************************ % Obtaining the percentage of QDs present in solution L=1; %comprimento da cubeta dado em cm for i=1:m Epsilon(i)=10043*(D(i)^(2.12)); C(i)=A_exp_aux(i)/(Epsilon(i)*L); %molar IF_int(i)=((IF_exp_max(i))/(I_lamp_aux(i)*QY(i)*Epsilon(i)*L*C(i))); end Q_QDs=((IF_int)/sum(IF_int))*100; %************************************************************************ %Finding QDs with the same diameter and adding them j_aux=0.0; count=0.0; for i=1:m for j=1:m if(j~=i) if (j~=j_aux) if(D(j)==D(i)) count=count+1.0; aux_D_s(count)=D(j); j_aux(count)=j; Q_QDs(i)=Q_QDs(i)+Q_QDs(j); Q_QDs(j)=0.0; end end end end end count=0.0; for i=1:m

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if(Q_QDs(i)~=0.0) count=count+1.0; Q_QDs_aux(count)=Q_QDs(i); D_Q_QDs_aux(count)=D(i); end end %************************************************************************ % Graphs figure(1); bar(D_Q_QDs_aux,Q_QDs_aux,5,'r','linewidth',aa);hold on; ylabel('P(%) ','fontsize',ft,'fontweight','bold'); set(h1,'linewidth',2,'fontsize',ft,'fontweight','bold');