Nonlinear polariton effects in naphthalene

Thesis/Dissertation · Tue Jan 01 00:00:00 EST 1985

OSTI ID:6921566

Stevenson, S H

Resonant second harmonic generation (SHG) and two-photon excited emission (TPE) were studied in pure, strain-free crystals of naphthalene at frequencies near that of the (0,0) a-exciton in order to probe the relationship between the two signals and to investigate the effect of polariton states on second order nonlinearities in molecular crystals. The strong coupling of the 31473 cm/sup -1/ exciton in naphthalene to the photon field dictates the second-order nonlinear behavior of naphthalene crystals at frequencies near half-resonance. The dynamics of polaritons produced coherently via nonlinear interactions is shown to deviate in a controllable way from the dynamics of the one-photon polaritons produced in a linear experiment. The nature of the excitation remains principally that of an exciton. The necessity of using a strong coupling model to explain orientational dispersion and intensity and lineshape behavior is established. The experimental angular frequency dispersion of the SHG and TPE signals are fit to theoretical polariton dispersion curves. The orientation of the naphthalene optical indicatrix at 31475 cm/sup -1/ is shown to be very nearly the same as that reported for visible light. The temperature dependences of the SHG and TPE signal intensities are successfully predicted from the polariton fusion model by inclusion of temporal damping in the fusion rate expression. The shapes of the SHG and TPE profiles are compared to shapes predicted from the semi-classical theory.

• Research Organization: Iowa State Univ. of Science and Technology, Ames (USA)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6921566
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
NAPHTHALENE
MULTI-PHOTON PROCESSES
CRYSTALS
EMISSION
EXCITED STATES
EXCITONS
EXPERIMENTAL DATA
NONLINEAR OPTICS
NONLINEAR PROBLEMS
TEMPERATURE DEPENDENCE
AROMATICS
CONDENSED AROMATICS
DATA
ENERGY LEVELS
HYDROCARBONS
INFORMATION
NUMERICAL DATA
OPTICS
ORGANIC COMPOUNDS
QUASI PARTICLES
400500* - Photochemistry