title: Transmittance and optical constants of Ca films in the 4-1000  eV spectral range.
abstract: The low expected absorption of Ca in the extreme ultraviolet (EUV) makes it an attractive material for multilayers and filters because most materials in nature strongly absorb the EUV. Few optical constant data had been reported for Ca. In this research, Ca films of various thicknesses were deposited on grid-supported C films and their transmittance measured in situ from the visible to the soft x-rays. The measurement range contains M2,3 and L2,3 absorption edges. Transmittance measurements were used to obtain the Ca extinction coefficient k. A minimum k of 0.017 was obtained at ∼23  eV, which makes Ca a promising low-absorption material for EUV coatings. A second spectral range of interest for its low absorption is below the Ca L3 edge at ∼343  eV. Measured k data and extrapolations were used to calculate the refractive index n using Kramers-Krönig relations. This is the first self-consistent data set on Ca covering a wide spectral range including the EUV.
authors.forename: Luis Rodríguez-de
authors.initials: LR
authors.lastname: Marcos
authors.forename: Juan I
authors.initials: JI
authors.lastname: Larruquert
authors.forename: Manuela
authors.initials: M
authors.lastname: Vidal-Dasilva
authors.forename: José A
authors.initials: JA
authors.lastname: Aznárez
authors.forename: Sergio
authors.initials: S
authors.lastname: García-Cortés
authors.forename: José A
authors.initials: JA
authors.lastname: Méndez
authors.forename: Luca
authors.initials: L
authors.lastname: Poletto
authors.forename: Fabio
authors.initials: F
authors.lastname: Frassetto
authors.forename: A
authors.initials: A
authors.lastname: Marco Malvezzi
authors.forename: Daniele
authors.initials: D
authors.lastname: Bajoni
authors.forename: Angelo
authors.initials: A
authors.lastname: Giglia
authors.forename: Nicola
authors.initials: N
authors.lastname: Mahne
authors.forename: Stefano
authors.initials: S
authors.lastname: Nannarone