March 2013

Issue 53


Job Opening


At Department of Process and Chemical Engineering, University of Bremen, Germany, there is an open position for a

Physicist   Structural characterization of mesoporous layers using light scattering

Measurement and simulation of light scattering.


The position is available within the Research Training Group MIMENIMA

Further information is available from:
Dr.-Ing. Thomas Wriedt
Tel. ++49-421-218-51250





The Optical Characterization of Atmospheric Aerosols workshop

Congress Centre, Smolenice SAS, Slovak Republic, November 5-7 2013.


Workshop website :


The main goal of the workshop is to present an opportunity for scientist in different fields to meet and form efficient collaborations in the research of atmospheric aerosols.


Characterizing properties of atmospheric aerosols is a multidisciplinary topic. Researchers include environmental scientists of all disciplines, together with theoretical physicists interested in scattering properties of irregularly shaped particles. Great progress in light-scattering theory discerned in the last several years makes it possible to treat arbitrarily shaped particles with anisotropic optical properties and inclusions. Optical methods appear to be a desirable technology for detection, primarily because such technology is rapid, the components are inexpensive, and the techniques can be automated, requiring no chemical reagents. Such methods are based on the fundamental principles of electromagnetic interaction with small particles, i.e., measurement and analysis of the scattered light. The meeting aim is to bring together the experts working in different fields of science to discuss the current state of the art and to formulate new research directions. The conference aim is to facilitate a more intensive development in these topics:



1. Aerosol Composition

2. Instrumentation

3. Aerosol Optical Modeling

4. Remote sensing


The workshop will take place at the Castle Smolenice, Slovakia. Because of its remote location, attendees will meet in Bratislava prior to the conference, taking advantage of its accessibility, especially to Partner participants. Attendees will be transferred by bus to Castle Smolenice, Slovakia, where they will remain until the final day. The Castle Smolenice has superb conference facilities at a greatly reduced cost. The restricted location also will ensure that attendees can devote their full attention to the task on hand. The last day of the conference, participants will return by bus to Bratislava.



New Paper


Absorption efficiencies of forsterite. I: DDA explorations in grain shape and size

Sean S. Lindsay1, Diane H. Wooden2, David E. Harker3, Michael S. Kelley4, Charles E. Woodward5 and Jim R. Murphy6

1Department of Earth and Planetary Sciences, University of Tennessee, USA

2Space Science Division, NASA Ames Research Center, USA

3Center for Astrophysics and Space Sciences, University of California, San Diego, USA

4Department of Astronomy, University of Maryland, USA

5Minnesota Institute of Astrophysics, University of Minnesota, USA

6Department of Astronomy, New Mexico State University, USA


We compute the absorption efficiency (Qabs) of forsterite using the discrete dipole approximation (DDA) in order to identify and describe what characteristics of crystal grain shape and size are important to the shape, peak location, and relative strength of spectral features in the 8 - 40 μm wavelength range. Using the ddscat code, we compute Qabs for non-spherical polyhedral grain shapes with aeff = 0.1 μm. The shape characteristics identified are: 1) elongation/reduction along one of three crystallographic axes; 2) asymmetry, such that all three crystallographic axes are of different lengths; and 3) the presence of crystalline faces that are not parallel to a specific crystallographic axis, e.g., non-rectangular prisms and (di) pyramids. Elongation/reduction dominates the locations and shapes of spectral features near 10, 11, 16, 23.5, 27, and 33.5 μm, while asymmetry and tips are secondary shape effects. Increasing grain sizes (0.1 - 1.0 μm) shifts the 10, 11 μm features systematically towards longer wavelengths and relative to the 11 μm feature increases the strengths and slightly broadens the longer wavelength features. Seven spectral shape classes are established for crystallographic a-, b-, and c-axes and include columnar and platelet shapes plus non-elongated or equant grain shapes. The spectral shape classes and the effects of grain size have practical application in identifying or excluding columnar, platelet or equant forsterite grain shapes in astrophysical environs. Identification of the shape characteristics of forsterite from 8 - 40 μm spectra provides a potential means to probe the temperatures at which forsterite formed.


Accepted for publication in The Astrophysical Journal

Available from arXiv:1302.0788 (  )



See recently indexed and summarized papers on the optics of particles and dispersions in TPDSci:


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