Laser applications to chemical and environmental analysis: introduction

The use of Gaussian elimination with backsubstitution for matrix inversion in scattering theories is discussed. Within the framework of the T-matrix method (the state-of-the-art code by Mishchenko is freely available at http://www.giss.nasa.gov/~crmim), it is shown that the domain of applicability of Mishchenkoʹs FORTRAN 77 (F77) code can be substantially expanded in the direction of strongly absorbing particles where the current code fails to converge. Such an extension is especially important if the code is to be used in nanoplasmonic or nanophotonic applications involving metallic particles. At the same time, convergence can also be achieved for large nonabsorbing particles, in which case the non-Numerical Algorithms Group option of Mishchenkoʹs code diverges. Computer F77 implementation of Mishchenkoʹs code supplemented with Gaussian elimination with backsubstitution is freely available at http://www.wave-scattering.com