Dispersion of Surface and Bulk Phonon‐Polaritons on α‐Quartz Measured by Attenuated Total Reflection

Infrared reflection and Raman spectra of single crystals of 7Li,GA03 and 6Li,Ge03 containing 7.42 and 9.10% of 6Li and 'Li, respectively, are measured and the oscillator parameters ;LO, $TO, y~o ,and y r o determined using the Kurosawa dispersion relation. The experimental attenuated total reflection spectra are in good agreement with the calculated polariton dispersion curves. The resonance type interactions between parent and isotopic impurity deformation modes are interpreted; the behaviour of the corresponding phonons depends on their symmetry species.Les spectres infrarouge et Raman de monocristaux de 'LiGeO, et 6Li,Ge03, contenant 7,42 et 9,10% de 6Li et 'Li, respectivement, ont btB analyses e t les parametres ;LO, ;TO, y~o , et TO de l'oscillateur ont btb determines i partir de la relation de dispersion de Kurosawa. Les spectres obtenus par reflexion totale attbnube sont en bon accord avec les courbes de dispersion du polariton calculbes. Des interactions resonantes ont Ate mises en evidence entre modes de deformation de I'isotope preponderant et de l'impuretb isotopique ; le comportement des phonons correspondants est diffbrent suivant leur type de symbtrie.

Section: Isotopic Impurity Modes and Polariton Dispersion Curvesmentioning

confidence: 99%

“…[6] and Falge et al [7]. Different values of polariton wave vectors were obtained by ATR technique using transverse electric polarization and varying incident angle from 25" to 60" and media such as AgCl and KRS-5 with known reflection indices.…”

Section: Experimental and Calculations A )mentioning

confidence: 99%

Isotopic Impurity Modes and Polariton Dispersion in Li₂GeO₃ Crystals

Orel¹,

Klanjšek²,

Moiseenko³

et al. 1985

“…Outside of the hatched areas the reflectivity is much smaller. The curves and lines which surround the areas of high reflectivity in the (w, k) diagram experimentally are found by the turning points of the edges of the reflection bands [6], as is shown in Fig. 5b and c by the marks.…”

Section: Results For A-quartzmentioning

confidence: 98%

Directional dispersion of polar phonons measured by infrared reflection

Falge¹,

Schuller²,

Börstel

1976

Self Cite

The dispersion of all polar optical phonons may be measured by the attenuated total reflection method. It is shown how the directional dispersion of the extraordinary polar phonons in uniaxial crystals is obtained in a similar way. I n the (w, k) diagram the areas of high reflectivity for transverse magnetic polarized incident radiation are determined by curves which have for k -t 0 the same frequencies as extraordinary phonons propagating in an infinite crystal for k -00. At arbitrary crystal cuts these curves are boundaries for the existence of surface phonon-polaritons. The method allows measuring the complete directional dispersion of t-t and 1-1 branches of Raman-inactive polar phonons, too.Die Dispersion aller polaren optischen Phononen kann durch die Methode der verhinderten Totalreflexion gemessen werden. ER wird gezeigt, wie die Richtungsdispersion der auBerordentlichen polaren Phononen in einachsigen Kristallen auf iihnliche Weise erhalten wird. Im

“…Because the dispersion curves are calculated without any damping this effect is not taken into account. As is shown in [15] for 8 = 0" and 6 = 90" damping can be included by calculating the reflectivity with a formula given in [16]. The dispersion curves then are defined by the minima of reflection [17].…”

Section: Resultsmentioning

confidence: 99%

Dispersion of Generalized Surface Phonon Polaritons on α‐Quartz Observed by Attenuated Total Reflection

Falge

Börstel

Otto³

1974

Self Cite

123Real and virtual excitation generalized surface polaritons are investigated on a 45' cut of an u-quartz crystal. For the wave vector of the surface polariton coplanar with the normal to the surface and the optical axis they are transverse magnetic polarized extraordinary waves. The experimental results agree with calculated dispersion curves. By attenuated total reflection for transverse magnetic polarized radiation it is shown that virtual excitation generalized surface polaritons exist only for certain ranges of the angle between the surface and the optical axis.Es werden reel1 und virtuell angeregte, verallgemeinerte Oberflachenpolaritonen fur den 45 "-Schnitt eines u-Quarz-Kristalls untersucht. Wenn der Wellenvektor des Oberfliichenpolaritons koplanar mit der Normalen zur Oberfliiche und der optischen Achse ist, sind sie transversal magnetisch polarisierte, aul3erordentliche Wellen. Die experimentellen Ergebnisse stimmen mit berechneten Dispersionskurven uberein. Durch verhinderte Totalreflektion fur transversal magnetisch polarisierte Strahlung wird gezeigt, daB virtuell angeregte, verallgemsinerte Oberflachenpolaritonen nur innerhalb von bestimmten Bereichen des Winkels zwischen Oberflache und optischer Achse existieren.