by Graeme Wardlaw
Abstract:
A NIR/VIS/UV Grating Spectrometer and a MIR BOHEM Interferometer were used to measure the reflectance of single crystal MBe13 compounds (M=U, Yb, La). A technique is employed such that the sample acts as its own reference, hence the effect of crystal surface features is eliminated and the sample and reference need not have identical dimensions. The three crystals produced a family of similar reflectance curves. The data obtained for UBe13 agreed well with literature in the measured region of 400 cm-1 - 32,000 cm-1. Comparative literature data for YBe13 and LaBe13 is not available. A Kramers-Kronig transformation of the reflectance data produced the optical conductivity of each crystal. Good agreement with literature was found for UBe13. An analysis was carried out on the imaginary part of the dielectric function for each crystal to obtain the plasma frequency and free carrier scattering rate so that the Drude contribution could be extracted from the overall optical conductivity. Upon subtracting the Drude contribution from the total conductivity to yield the interband contribution, it was found that UBe13 shows some moderate structure in the low frequency region. YBe13 and LaBe13 showed well pronounced peaks in the same range, providing evidence of low frequency interband transitions associated with the M-atom.
Reference:
Graeme Wardlaw, "Optical properties of MBe13 compounds (M=U, Yb, La) from the mid-infra-red to the UV", 1998.
Bibtex Entry:
@bachelorsthesis{1998W,
title={Optical properties of MBe<sub>13</sub> compounds (M=U, Yb, La) from the mid-infra-red to the UV},
author={Graeme Wardlaw},
month={June},
year={1998},
abstract={A NIR/VIS/UV Grating Spectrometer and a MIR BOHEM Interferometer were used to measure
the reflectance of single crystal MBe<sub>13</sub> compounds (M=U, Yb, La). A technique
is employed such that the sample acts as its own reference, hence the effect of crystal
surface features is eliminated and the sample and reference need not have identical
dimensions. The three crystals produced a family of similar reflectance curves. The data
obtained for UBe<sub>13</sub> agreed well with literature in the measured region of
400 cm<sup>-1</sup> - 32,000 cm<sup>-1</sup>. Comparative literature data for YBe<sub>13</sub> and
LaBe<sub>13</sub> is not available. A Kramers-Kronig transformation of the reflectance
data produced the optical conductivity of each crystal. Good agreement with literature
was found for UBe<sub>13</sub>. An analysis was carried out on the imaginary part of the
dielectric function for each crystal to obtain the plasma frequency and free carrier
scattering rate so that the Drude contribution could be extracted from the overall
optical conductivity. Upon subtracting the Drude contribution from the total conductivity
to yield the interband contribution, it was found that UBe<sub>13</sub> shows some moderate
structure in the low frequency region. YBe<sub>13</sub> and LaBe<sub>13</sub> showed well
pronounced peaks in the same range, providing evidence of low frequency interband
transitions associated with the M-atom.},
note={Supervised by M. Reedyk}
}