Related papers: Triple Junction and Grain Boundary Influences on C…
Polar ice cores play a central role in studies of the earth's climate system through natural archives. A pressing issue is the analysis of the oldest, highly thinned ice core sections, where the identification of paleoclimate signals is…
Grains of ice are formed spontaneously when water vapor is injected into a weakly-ionized laboratory plasma in which the background gas has been cooled to cryogenic temperatures comparable to those of deep space. These ice grains are…
Targeted ultra-high resolution Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) analysis of an ice core drilled in the Pamir Mountains of Central Asia (CA) records changes in seasonal patterns of atmospheric…
Currently ~36 different absorption bands have been detected in the infrared spectra of cold, dense interstellar and circumstellar environments. These are attributed to the vibrational transitions of ~17 different molecules frozen on dust…
Previous computations of low temperature Rosseland and Planck mean opacities from Alexander & Ferguson (1994) are updated and expanded. The new computations include a more complete equation of state with more grain species and updated…
The ice microstructure (grain boundaries) is a key feature used to study ice evolution and to investigate past climatic changes. We studied a deep ice core, in Dome Concordia, Antarctica, which records past mechanical deformations. We…
The Galactic Cold Cores project has made Herschel observations of 116 fields where the Planck survey has found signs of cold dust emission. The fields contain sources in different environments and different phases of star formation. The…
At very fine grain sizes, grain boundary segregation can deviate from conventional behavior due to triple junction effects. While this issue has been addressed in prior work for substitutional alloys, here we develop a framework that…
Aligned interstellar grains produce polarized extinction (observed at wavelengths from the far-ultraviolet to the mid-infrared), and polarized thermal emission (observed at far-infrared and submm wavelengths). The grains must be quite…
Lake ice within three Advanced Microwave Scanning Radiometer on EOS (AMSR-E) pixels over the Great Bear and Great Slave Lakes have been simulated with the Canadian Lake Ice Model (CLIMo). The resulting thicknesses and temperatures were fed…
Grain Boundaries (GB) whose energy is larger than twice the energy of the solid/liquid interface exhibit the premelting phenomenon, for which an atomically thin liquid layer develops at temperatures slightly below the bulk melting…
Within the project Galactic Cold Cores we are carrying out Herschel photometric observations of cold interstellar clouds detected with the Planck satellite. The three fields observed as part of the Herschel science demonstration phase (SDP)…
Interstellar ices are largely composed of frozen water. It is important to derive fundamental parameters for H$_2$O ice such as absorption and scattering opacities for which accurate complex refractive indexes are needed. The primary goal…
It has been implicitly assumed that ices on grains in molecular clouds and proto planetary disks are formed by homogeneous layers regardless of their composition or crystallinity. To verify this assumption, we observed the H2O deposition…
The structure and evolution of grain boundaries underlies the nature of polycrystalline materials. Here we describe an experimental apparatus and light reflection technique for measuring disorder at grain boundaries in optically clear…
We investigate the hyperfine transition of $^{3}\mathrm{He}^{+}$ as a promising probe of the IGM during the final stages of helium reionization. Utilising the most recent helium reionization simulation, we generate three-dimensional maps of…
We describe an optical scattering study of grain boundary premelting in water ice. Ubiquitous long ranged attractive polarization forces act to suppress grain boundary melting whereas repulsive forces originating in screened Coulomb…
We observe an inverted crossover resonance in $\pi$-driven four-level systems, where $F'-F=0,+1$. The signal is observed through saturated absorption spectroscopy of the $(6s^{2})$ $^{1}S_{0}$ $-$ $(6s6p)$ $^{3}P_{1}$ transition in…
The structure and composition of simple ices can be modified during stellar evolution by protostellar heating. Key to understanding the involved processes are thermal and chemical tracers that can diagnose the history and environment of the…
Two different silicate/water ice mixtures representing laboratory analogues of interstellar and circumstellar icy grains were produced in the laboratory. For the first time, optical constants, the real and imaginary parts of the complex…