Optical spectroscopy of ErFe3(BO3)4: detection of phase transitions and crystal-field levels of the Er3+ ground multiplet

High-resolution spectra of oriented ErFe3(BO3)4 single crystals are registered in the spectral range 500 – 8000 cm-1 at various temperatures (4 – 470 K). The temperature behaviour of the phonon mode at 976 cm-1 allowed us to register a structural phase transition at TS=431 K. The energies of crystal-field levels of the ground 4I15/2 and the first excited 4I13/2 multiplets of the Er3+ ion are determined in the paramagnetic state of ErFe3(BO3)4. The exchange splitting of the ground Kramers doublet in the magnetically ordered state was found to be Δ0=6.3±1 cm-1. The interference occurring due to birefringence in the single crystals was also registered. The temperature dependence of the position of the maximum of the interference band demonstrates two anomalies, at TN and TS, associated with the phase transitions in ErFe3(BO3)4.

Photon Emission Spectra of FETs as Obtained by InGaAs Detector

In this work we present spectrally resolved photon emission microscopy (SPEM) measurements for short-channel FETs acquired through the backside of the Si substrate using InGaAs detector. Two spectrum resolution methods have been used: continuous using a prism and discrete using a set of interference band-pass filters. The photon emission (PE) spectra have been corrected for the background / noise of the detector; they have been calibrated with respect to the system optical transmission function and corrected for the absorption on free carriers in the remaining layer of Si substrate. We discuss all the standardization aspects thoroughly as they are crucial in order to obtain correct device-intrinsic PE spectral information. Finally, we present the spectral results for FET devices operated in various operating conditions.

New design of interference band-pass infrared filter

The new design of the interference band-pass infrared filters is proposed. The analytic expressions for the analysis structure “layer with the high refractive index — interference mirror — layer with the high refractive index” are obtained. The refractive indices optimal and thicknesses of individual layers that limited interference mirror are obtained.

Improvement of Optical Resolution through Chip Backside Using FIB Trenches

Optical spatial resolution improvement using local focused ion beam (FIB) assisted silicon material removal was investigated. Two types of test structures were chosen for imaging-resolution characterization to be able to use two ways of measuring resolution. Samples of various remaining bulk silicon thicknesses were prepared and characterized in terms of image quality and spatial resolution. The resulting remaining bulk Si thickness was measured using reflectance spectrometry. Images were acquired using halogen-lamp illumination and reflected light detection using a cooled Si-CCD detector. To investigate the image quality at various wavelengths, a set of interference band-pass filters was applied.

Affinity binding of non-histone chromatin proteins to the X chromosome of Drosophila by in situ chromatin reconstitution and its significance

Cytophotometric analysis of the in situ binding affinity of non-histone chromosomal protein (NHCP) to the polytenic X chromosome and autosome of Drosophila melanogaster has been carried out using Feulgen-Napthol Yellow S staining technique. The results reveal that the mean transformed absorbance ratio (male:female) with a 547 nm interference band filter for the two specific segments of the X chromosome is close to 0.5, while for a specific segment of an autosome it is close to 1.0, in the two sets of control; namely, the positive control (no treatment) and the negative control (treated with 1 M-urea+2M-NaCl) as well as in the reconstituted chromosomal preparations, which received 1 M-urea+2M-NaCl and the NHCP isolated from D. melanogaster. In contrast, the transformed absorbance ratios (male:female) with a 433 nm interference band filter yielded an interestingly different result. The ratios with a 433 nm filter for the X chromosome segments are significantly greater than 0.5 in all three sets of experiments. This finding by itself suggests that the NHCP binding affinity is dissimilar for the X chromosomes of male and female. When the 433 to 547 nm absorbance ratios were compared among the three sets, the data clearly revealed that in both positive control and NHCP reconstituted samples, the absorbance ratios (i.e. 433:547 nm) are significantly different between X chromosomes from males and those from females, while they are different between autosomes from males and females. The ratios are also not significantly different between male and female, either for the X chromosome or for the autosome in the negative control. These findings, therefore, suggest that there is a stronger binding affinity of NHCP for the male X chromosome of Drosophila, and reinstate the view that the X-chromosomal hyperactivity in male Drosophila is the consequence of a regulated organizational change in the DNA template.

I. A wave-length comparator for standards of length: An instrument for fine measurement in wave-lengths of light. - With an appendix on the use of wave-length rulings as defining lines on standards of length

The following is a brief account of a new apparatus for fine measurement in wavelengths of light, designed primarily as a comparator for the measurement in wavelengths of the difference between a standard of length, either a line or an end measure bar—the Imperial Standard Yard, for instance—and any duplicate or similar bar proposed to be employed as a derived standard. The instrument is also, however, the most perfect instrument yet devised for measurement in wavelengths in general, and performs its functions so admirably as to render it highly desirable that a description should now be published concerning it. It has been constructed to the designs and under the supervision of the author for the Standards Department of the Board of Trade, and this account of it is communicated to the Royal Society with the permission of the President of the Board of Trade. The principle underlying the instrument is that of the author’s interferometer, which has also proved so successful in its application, in the interference dilatometer, to the determination of the thermal expansion of small bodies by the Fizeau method, and in the elasmometer, to the measurement of the elastic bending of a small plate or bar under a given weight applied at the centre. The essence of the interferometer is that homogeneous light, of a definite wave-length, corresponding to a single spectrum line—isolated with the aid of a constant-deviation prism from the spectrum derived from a cadmium or hydrogen Geissler tube, or a mercury lamp—is directed by an autocollimation method, ensuring identity of path of the incident and reflected rays, normally upon two absolutely plane surfaces, arranged close to each other, and nearly, but not absolutely, parallel; the two reflected rays give rise, by their interference, to rectilinear dark interference bands on a brilliantly illuminated background in the colour corresponding to the selected wave-length. In the instrument now described, one of these two reflecting surfaces concerned in the production of the interference bands is carried by, and moves absolutely with, one of the two microscopes employed to focus the fiducial marks, or "defining lines", determinative of the length of the standard, the other surface being absolutely fixed. The movement of either of the surfaces with respect to the other causes the interference bands to move, and the extent of the movement of the surface is equal to half the wave-length of the light employed for every interference band that moves past a reference mark carried by the fixed surface. The movement of the microscope parallel to itself and to the length of the standard bar is thus measured by counting the number of bands and the initial and final fractions of a band which are observed to pass the reference spot during the movement, and multiplying that number by the half wave-length of the light radiation used in the production of the bands. It is only necessary, therefore, in order to compare the lengths of two bars, (1) to place the bar of known length, say, the Imperial Standard Yard, under the two microscopes so that the two defining lines are adjusted in each case between the pair of parallel spider-lines carried by each of the micrometer eye-pieces; (2) to replace the standard by the copy to be tested, so that the defining line near one end is similarly adjusted under the corresponding microscope, then, if the other defining mark is not also automatically adjusted under the second microscope which carries the interferometer glass surface, as it should be if it is an exact copy, (3) to traverse that microscope until it is so adjusted, and (4) to observe and count the number of interference bands which move past the reference spot during the process. The product of this number into the half wave-length of the light used to produce the bands thus obviously affords the difference between the two lengths included between the defining marks on the two bars.

The use of wave-length rulings as a defining lines on standards of length

The delicacy of the method of measurement in wave-lengths described in the preceding communication calls for a corresponding refinement in the engraved lines, which form the defining lines of the length of a standard yard or metre or other line-measure bar. The defining lines on the Imperial Standard Yard are sharp-edged, but contain the equivalent of 40 interference bands of red light in their thickness, and the Benoît defining lines of the platinum-iridium copy made in 1902 are not only very ragged-edged out contain 15 interference bands in their thickness. The author has been in communication with Mr. J. H. Grayson, of Melbourne, whose fine rulings have recently evoked such interest among microscopists, and after a ling investigation has found that wonderfully satisfactory rulings on the scale of 40,000 to the inch can be made on polished speculum metal, covered with a thin cover-glass. Now the forty-thousandth of an inch is a single wave-length of red light (for H α = 1/38710 inch, and Cd red = 1/39459 inch), so that the interval between any adjacent pair of these lines is equivalent to only two interference bands. The thickness of each line, which is absolutely sharp-edged, is less than a single interference band. The author has therefore devised a defining mark in these rulings, which he terms a "Tutton location signal," to distinguish it from the "Benoît defining line." It consists of five such parallel lines spaced one forty-thousandth of an inch apart, with a pair of strong "finder" lines outside them and parallel to them, and another pair of similar finder lines perpendicularly transverse to them, to indicate a central part the lines for use. The central line of the five fine Grayson ruling is the defining line.