LARGE 2ND-HARMONIC GENERATION COEFFICIENTS OF BIS(BENZYLIDENE)CYCLOALKANONES ESTIMATED BY THE 2ND-HARMONIC WAVE GENERATED WITH THE EVANESCENT-WAVE TECHNIQUE

The second-harmonic generation (SHG) coefficients (d) in a series of n ovel organic materials, i.e. bis(benzylidene)cycloalkanone derivatives , were estimated by means of the second-harmonic wave generated with t he evanescent wave (SHEW) technique. As a result, it is found that sev eral compounds exhibit a large d coefficient, in particular, a promine nt coefficient 2.7 times as large as that of m-nitroaniline for 2,5-bi s(4'-methylbenzylidene)cyclopentanone (MBCP). An X-ray crystallographi c study reveals that the symmetry of MBCP is orthorhombic mm2. Compari son between d coefficients estimated by the SHEW and the Kurtz techniq ue is also made.