  We report some improved wave function for mesons taking linear confinement
term in standard QCD potential as parent and Coulombic term as perturbation
while applying quantum mechanical perturbation technique in solving Schrodinger
equation with such a potential. We find that Airy's infinite series appears in
the wave-function of the mesons. We report our calculations on the Isgur-Wise
function and its derivatives for heavy-light mesons, within this framework.
