Full-profile fitting of emission spectrum to determine transition intensity parameters of Yb3＋ ：GdTaO4

The Judd-Ofelt theoretic transition intensity parameters A（tp）k of luminescence of rare-earth ions in solids are important for the quantitative analysis of luminescence.It is very difficult to determine them with emission or absorption spectra for a long time.A ＂full profile fitting＂ method to obtain A（tp）k in solids with its emission spectrum is proposed,in which the contribution of a radiative transition to the emission spectrum is expressed as the product of transition probability,line profile function,instrument measurement constant and transition center frequency or wavelength,and the whole experimental emission spectrum is the sum of all transitions.In this way,the emission spectrum is expressed as a function with the independent variables intensity parameters A（tp）k,full width at half maximum（FWHM） of profile functions,instrument measurement constant,wavelength,and the Huang-Rhys factor S if the lattice vibronic peaks in the emission spectrum should be considered.The ratios of the experimental to the calculated energy lifetimes are incorporated into the fitting function to remove the arbitrariness during fitting A（tp）k and other parameters.Employing this method obviates measurement of the absolute emission spectrum intensity.It also eliminates dependence upon the number of emission transition peaks.Every experiment point in emission spectra,which usually have at least hundreds of data points,is the function with variables A（tp）k and other parameters,so it is usually viable to determine A（tp）k and other parameters using a large number of experimental values.We applied this method to determine twenty-five A（tp）k of Yb（3＋） in GdTaO4.The calculated and experiment energy lifetimes,experimental and calculated emission spectrum are very consistent,indicating that it is viable to obtain the transition intensity parameters of rare-earth ions in solids by a full profile fitting to the ions＇ emission spectrum.The calculated emission cross sections of Yb（3＋）：GdTaO4 also indicate that the F-L formula gives larger values in the wavelength range with reabsorption.

Particle Swarm Optimization with Directed Mutation

In the standard particle swarm optimization(SPSO),the big problem is that it suffers from premature convergence,that is,in complex optimization problems,it may easily get trapped in local optima.In order to mitigate premature convergence problem,this paper presents a new algorithm,which is called particle swarm optimization(PSO) with directed mutation,or DMPSO.The main idea of this algorithm is to "let the best particle(the smallest fitness of the particle swarm) become more excellent and the worst particle(the largest fitness of the particle swarm) try to be excellent".The new algorithm is tested on a set of eight benchmark functions,and compared with those of other four PSO variants.The experimental results illustrate the effectiveness and efficiency of the DMPSO.The comparisons show that DMPSO significantly improves the performance of PSO and searching accuracy.