Optical Measurements on Thin Films of Condensed Gases at Low Temperatures*

Krüger, J.; Ambs, William J.

doi:10.1364/josa.49.001195

Cited by 53 publications

(26 citation statements)

References 4 publications

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“…&2= 20' cos8 = 2cp s3 = 20'sin8 = 2x· (15) H ence t he state of polarization Ill ay now be represetIted by tbe plane p olar coordinates 20' a nd 8, and this corr esponds to r epr esen ting as a plane surface t he portion of the sphere on t he equ ato r ar ound th e azimuth r epresen t ing the plane of in cidence, i. e., around I p. U nder the above ass ump t ions, t he states of polarization of t he lig ht issuing from the polarizer all lie on t be line 20' sin 8= 2x p = _ X_ . This process is illustrated in figure 6, where 1 -] ' represents the locus of points representing the incident light and R -R' the reflected light.…”

Section: Alinementmentioning

confidence: 99%

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Measurement of the thickness and refractive index of very thin films and the optical properties of surfaces by ellipsometry

McCrackin¹,

Passaglia²,

Stromberg³

et al. 1963

J. RES. NATL. BUR. STAN. SECT. A.

617

256

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The use of t he ellipsometer for t he m eas urpment of the thickn ess a nd refra ctive index of very thin film s is reviewed . The P o in care sphere representatio n of t he state of p ola rizat io n of light is de \'elop ed a nd used to desc ribe t he reflection process. D etails of the operation of t he ellipso meter a rc examined criticall y. A co mpu tatio nal mC'thod is prese nted by whi ch the thickness of a film of known refractive ind ex on a re fl ecting s ubstrate of known optical co nstants ma y be calculated direc t ly from the ellipsometer r ea din g~. A met hod for co mpu tin g both the refractivc index a nd thickn ess of an unkn own film is also d e veloped. These meth ods have been applied to the det erminat ion of th e th ick ness of a n adso rbed water layer on chromium ferrotyp e p la t es and on gold s urfaces. In th c former case the t hi ck ness , ras 23 to 27 A, a nd in the lat,tc r was 3 to 5 A. Th e meas urement of the th ickness and refractive index of barium fiu ori de film s c\'aporated 0 11 ch romiu m fC'ITotyp e s urfaces is used a s a n illust ration of t h e simu ltaneous d eterlllin a tion of these t wo qu a ntiti es .

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Section: Alinementmentioning

confidence: 99%

“…Cells have been used for ellipsometer meftsurements in vacuum or gaseous environments [2,14,15] and under liquids [2 ]. The cell shown in figure 9 has been used in our studies for measurements under liquids.…”

Section: Cellsmentioning

confidence: 99%

Measurement of the thickness and refractive index of very thin films and the optical properties of surfaces by ellipsometry

McCrackin¹,

Passaglia²,

Stromberg³

et al. 1963

J. RES. NATL. BUR. STAN. SECT. A.

617

256

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“…None of the oxides of iron whose refractive indices are known or indeed any of the possible solids whose values are known which could constitute the film have a refractive index lower than that of the nitrite solution. On the other hand, an oxygen film (14) or an adsorbed nitrite film would probably have a refractive index lower than the solution.…”

Section: Journal Of the Electrochemical Societymentioning

confidence: 99%

Optical Studies of the Formation and Breakdown of Passive Films Formed on Iron Single Crystal Surfaces in Inorganic Inhibitor Solutions

Krüger

1963

J. Electrochem. Soc.

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Polarized light was used to measure the thickness and optical properties of passive films as they were forming while simultaneous electrochemical measurements were being made. The film formation studies showed that a change in film thickness of 15-20A was associated with the onset of a passive potential. A direct, logarithmic-type law governed the growth of a semiconductor film with crystallographic orientation of the substrate having little effect.When iron surfaces prepared in an ultrahigh vacuum (a vacuum of the 10 -9 Torr order of magnitude), were passivated a 20A film formed instantaneously on the introduction of an air-saturated 0.1N NaNOf. This film then dissolved and a new film commenced to grow. A passive potential coincided with a film 15A thick. No such initial dissolution occurred when the solution contained only dissolved oxygen, the instantaneously formed film continuing to grow and a passive potential occurring after the growth of around 40A. When the solution contained no dissolved gases, the instantaneous film did not form.Film breakdown studies revealed that only the 20-30A film next to the metal was responsible for passivity even if thicker films were initially present. Studies of the sites of film breakdown showed that the number of sites was highest for films on {110) iron surfaces and that these sites were not related to points where dislocations intersected the surface. These studies support the oxide film theory of passivity.

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“…M is taken as 29.9 x 10 ~2 4 g, 17 / around the x axis as 1.024x 10 ~4 0 g-cm 2 , l7 and m for the v x mode as 1.595xl0~2 4 g. 17 To simulate the electronic screening of the anion, we use the optical dielectric constant € = 1.42. 18 Except for a few well-defined cases, 1 the lifetime of a molecular resonance is not an easy quantity to determine, and its value is generally uncertain. Hence, for the purpose of calculation, resonance energy widths ranging from 0.01 to 1.0 eV are considered.…”

Section: (T)=v[e(rt)n(r)coso]mentioning

confidence: 99%

Opening of new decay channels for core-excited resonances

Michaud

Sanche

1987

Phys. Rev. Lett.

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Electron-scattering cross sections for intramolecular and intermolecular vibrational excitation in amorphous solid H2O are reported for the incident energy range 1-18 eV. The origin of the feature for the stretching modes is ascribed to resonant scattering similar to the gas phase. Those in the translational and librational modes are shown to arise mainly from the interaction of a long-lived transient anion with the dipoles of the surrounding molecules.PACS numbers: 34.80. Gs, 63.50,+x, 79.20.Kz It is well established that the formation of temporary anion states or resonances play a dominant role in lowenergy electron-molecule scattering in the gas phase. 1 Recently, these resonance processes have been shown to occur in electron scattering from condensed molecular film. 2 " 6 Similarly to the gas phase, a resonance in condensed matter can be visualized as a temporary localization of an electron on a molecular lattice site. The localized electron wave function is so characterized by the symmetry derived from the various perturbed molecular orbitals involved in the process and by a lifetime (r). Thus, a resonance state has a time-dependent factor, i.e.,where E r is the resonance energy and V = h/r the energy width for decay. So far, their manifestation has been found exclusively in intramolecular vibrational excitation 2 and dissociative attachment 3 of the molecule located at the transient anion site. In this Letter, we report the determination of absolute cross sections between 1 and 18 eV for intramolecular and particularly for intermolecular vibrational excitations for electron scattering in amorphous ice. The features in the cross sections are correlated with shapeand core-excited resonances of the free molecule. We show, more specifically, that a transient anion state can decay into new channels consisting of the translational and librational modes of the surrounding molecular lattice.The measurements were performed with an electronenergy-loss (EEL) spectrometer and a cryogenic target. 4 With respect to the outward normal of the target, the angle of incidence 0o of the monochromator can be varied from 14° to 70°, and the angle of the analyzer 0d is fixed at 45° at the opposite azimuth. The apparatus is housed in a cryopumped UHV system capable of sustaining working pressures around 5xl0~n Torr. 4 In the present experiment, triply distilled H2O vapor was condensed on a polycrystalline platinum substrate held at 14 K. The thickness was estimated in situ by monitoring on the substrate the transmitted current, previously calibrated with respect to the absolute H2O coverage. 5 The incident current was 3x 10 ~1 0 A for a combined resolu-tion of 10 meV full width at half maximum (FWHM). The incident energy EQ was calibrated within ±0.1 eV with respect to the vacuum level by measuring the onset of the transmitted current.EEL spectra for thirty layers of ice recorded at 0n = 14° and for Eo -7.2 and 9.2 eV are shown in Fig. 1. These can be compared with infrared and Raman spectra of ice. 7 The well-separated elastic...

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Optical Measurements on Thin Films of Condensed Gases at Low Temperatures*

Cited by 53 publications

References 4 publications

Measurement of the thickness and refractive index of very thin films and the optical properties of surfaces by ellipsometry

Measurement of the thickness and refractive index of very thin films and the optical properties of surfaces by ellipsometry

Optical Studies of the Formation and Breakdown of Passive Films Formed on Iron Single Crystal Surfaces in Inorganic Inhibitor Solutions

Opening of new decay channels for core-excited resonances

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