n ^ ( λ )=n( λ )−iκ( λ ) MathType@MTEF@5@5@+=feaagCart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHXgaruavP1wzZbItLDhis9wBH5garmWu51MyVXgarqqtubsr4rNCHbGeaGqipG0dh9qqWrVepG0dbbL8F4rqqrVepeea0xe9LqFf0xc9q8qqaqFn0lXdHiVcFbIOFHK8Feea0dXdar=Jb9hs0dXdHuk9fr=xfr=xfrpeWZqaaiqaciWacmGadaGadeaabaGaaqaaaOqaaiqad6gagaqcamaabmaabaGaeq4UdWgacaGLOaGaayzkaaGaeyypa0JaamOBamaabmaabaGaeq4UdWgacaGLOaGaayzkaaGaeyOeI0IaaeyAaiabeQ7aRnaabmaabaGaeq4UdWgacaGLOaGaayzkaaaaaa@458E@
where κ(λ) is the spectral absorption index and i= −1 MathType@MTEF@5@5@+=feaagCart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbbjxAHXgaruavP1wzZbItLDhis9wBH5garmWu51MyVXgarqqtubsr4rNCHbGeaGqipG0dh9qqWrVepG0dbbL8F4rqqrVepeea0xe9LqFf0xc9q8qqaqFn0lXdHiVcFbIOFHK8Feea0dXdar=Jb9hs0dXdHuk9fr=xfr=xfrpeWZqaaiqaciWacmGadaGadeaabaGaaqaaaOqaaiaabMgacqGH9aqpdaGcaaqaaiabgkHiTiaaigdaaSqabaaaaa@3905@
unit: 1