We analyse the global structure of the old stellar discs in 34 edge-on spiral galaxies. The radial and vertical exponential scale parameters of the discs are obtained by applying an improved two-dimensional decomposition technique to our I-band photometry. We find a clear increase in the disc scaleheight with maximum rotational velocity, in accordance with observations of the stellar velocity dispersions in galaxy discs. The range and maximum of the intrinsic flattening of the disc light seem to increase with both maximum rotational velocity and total HI mass. We use the disc flattening to estimate the disc contribution to the maximum rotational velocity, resulting in an average of 57+-22 percent. The disc light distributions are further investigated for the presence of radial truncations. We find that the radial light distributions of at least 20 spirals are truncated, corresponding to 60 percent of the sample. For small scalelength spirals, which are the most numerous in the local Universe, the results suggest that the average ratio of disc truncation radius to disc scalelength is at least four.Comment: 25 pages, 7 figures, appendix, Accepted for MNRAS (April 4 2002

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We report the writing of very high resolution tungsten containing dots in regular arrays by electron beam-induced deposition (EBID). The size averaged over 100 dots was 1.0 nm at fwhm. Because of the statistical spread in the dot size, large and small dots are present in the arrays, with the smallest having a diameter of only 0.7 nm at fwhm. To date these are the smallest features fabricated by EBID. We have also fabricated lines with the smallest having a width at fwhm of 1.9 nm and a spacing of 3.2 nm.

Dust extinction can be determined from the number of distant field galaxies seen through a spiral disk. To calibrate this number for the crowding and confusion introduced by the foreground image, González et al. (1998) andHolwerda et al. (2005a) developed the "Synthetic Field Method" (SFM), which analyses synthetic fields constructed by adding various deep exposures of unobstructed background fields to the candidate foreground galaxy field.The advantage of the SFM is that it gives the average opacity for area of galaxy disk without assumptions about either the distribution of absorbers or of the disk starlight. However it is limited by low statistics of the surviving field galaxies, hence the need to combine a larger sample of fields. This paper presents the first results for a sample of 32 deep HST/WFPC2 archival fields of 29 spirals.The radial profiles of average dust extinction in spiral galaxies based on calibrated counts of distant field galaxies is presented here, both for individual galaxies as well as for composites from our sample. The effects of inclination, spiral arms and Hubble type on the radial extinction profile are discussed.The dust opacity of the disk apparently arises from two distinct components; an optically thicker (A I = 0.5 − 4 mag) but radially dependent component associated with the spiral arms and a relatively constant optically thinner disk (A I ≈ 0.5 mag.). These results are completely in agreement with earlier work on occulted galaxies. The early

Electron-beam-induced deposition ͑EBID͒ is a versatile micro-and nanofabrication technique based on electron-induced dissociation of metal-carrying gas molecules adsorbed on a target. EBID has the advantage of direct deposition of three-dimensional structures on almost any target geometry. This technique has occasionally been used in focused electron-beam instruments, such as scanning electron microscopes, scanning transmission electron microscopes ͑STEM͒, or lithography machines. Experiments showed that the EBID spatial resolution, defined as the lateral size of a singular deposited dot or line, always exceeds the diameter of the electron beam. Until recently, no one has been able to fabricate EBID features smaller than 15-20 nm diameter, even if a 2-nm-diam electron-beam writer was used. Because of this, the prediction of EBID resolution is an intriguing problem. In this article, a procedure to theoretically estimate the EBID resolution for a given energetic electron beam, target, and gaseous precursor is described. This procedure offers the most complete approach to the EBID spatial resolution problem. An EBID model was developed based on electron interactions with the solid target and with the gaseous precursor. The spatial resolution of EBID can be influenced by many factors, of which two are quantified: the secondary electrons, suspected by almost all authors working in this field, and the delocalization of inelastic electron scattering, a poorly known effect. The results confirm the major influence played by the secondary electrons on the EBID resolution and show that the role of the delocalization of inelastic electron scattering is negligible. The model predicts that a 0.2-nm electron beam can deposit structures with minimum sizes between 0.2 and 2 nm, instead of the formerly assumed limit of 15-20 nm. The modeling results are compared with recent experimental results in which 1-nm W dots from a W͑CO͒ 6 precursor were written in a 200-kV STEM on a 30-nm SiN membrane.