Abstract. Continuous, in situ measurements of water vapor isotopic composition have been conducted in the North Atlantic, at the Bermuda Islands (32.26° N, 64.88° W), between November 2011 and June 2013, using a cavity ring-down spectrometer water vapor isotope analyzer and an autonomous self-designed calibration system. Meticulous calibration allows us to reach an accuracy and precision on 10 min average of δ18O, δ D, and d-excess of, 0.14, 0.85, and 1.1‰, verified using two parallel instruments with independent calibration. As a result of more than 500 days with 6-hourly data the relationships between deuterium excess, relative humidity (RH), sea surface temperature (SST), wind speed, and wind direction are assessed. From the whole data set, 84 % of d-excess variance is explained by a strong linear relationship with relative humidity. The slope of this relationship (−42.6 ± 0.4‰ % (RH)) is similar to the theoretical prediction of Merlivat and Jouzel (1979) for SST between 20 and 30 °C. However, in contrast with theory, no effect of wind speed could be detected on the relationship between d-excess and relative humidity. Separating the data set into winter, spring, summer, and autumn seasons reveals different linear relationships between d-excess and humidity. Changes in wind directions are observed to affect the relationships between d-excess and humidity. The observed seasonal variability in the relationship between d-excess and relative humidity underlines the importance of long-term monitoring to make accurate conclusions.

Abstract. Stable isotopes of water vapour are powerful indicators of meteorological processes on a broad range of scales, reflecting evaporation, condensation, and air mass mixing processes. With the recent advent of fast laser-based spectroscopic methods, it has become possible to measure the stable isotopic composition of atmospheric water vapour in situ at a high temporal resolution. Here we present results from such comprehensive airborne spectroscopic isotope measurements in water vapour over the western Mediterranean at a high spatial and temporal resolution. Measurements have been acquired by a customized Picarro L2130-i cavity-ring down spectrometer deployed onboard the Dornier 128 D-IBUF aircraft together with a meteorological flux measurement package during the HyMeX SOP1 (Hydrological cycle in Mediterranean Experiment special observation period 1) field campaign in Corsica, France, during September and October 2012. Taking into account memory effects of the air inlet pipe, the typical time resolution of the measurements was about 15-30 s, resulting in an average horizontal resolution of about 1-2 km. Cross-calibration of the water vapour measurements from all humidity sensors showed good agreement under most flight conditions but the most turbulent ones. In total 21 successful stable isotope flights with 59 flight hours have been performed. Our data provide quasi-climatological autumn average conditions and vertical profiles of the stable isotope parameters δD, δ 18 O, and d-excess during the study period. A d-excess minimum in the overall average profile is reached in the region of the boundary-layer top, possibly caused by precipitation evaporation. This minimum is bracketed by higher d-excess values near the surface caused by non-equilibrium fractionation, and a maximum above the boundary layer related to the increasing d-excess in very depleted and dry high-altitude air masses. Repeated flights along the same pattern reveal pronounced day-to-day variability due to changes in the large-scale circulation. During a period marked by a strong inversion at the top of the marine boundary layer, vertical gradients in stable isotopes reached up to 25.4 ‰ 100 m −1 for δD and 24.0 ‰ 100 m −1 for the dexcess.

An investigation of the feasibility of in situ monitoring of polymorphic transitions is presented. Focused beam reflectance measurement (FBRM) and particle vision and measurement (PVM) are used to study changes in crystal population and morphology during the transition of the δ-polymorph of D-mannitol to the thermodynamically stable β-form. The transformation is confirmed via off-line X-ray powder diffraction (XRPD). Nucleation and growth of β-form D-mannitol was detected and measured by FBRM/PVM when δ-form was added to a saturated solution of β-form D-mannitol. Raman spectroscopy is also introduced as an invaluable in situ identification technique for polymorphic crystallizations. The effect of particle size on the intensity of the Raman spectrum is investigated using slurries of D-mannitol and sucrose in toluene. Raman spectroscopy successfully distinguished a mixture of sucrose and D-mannitol in toluene, and a linear correlation between Raman peak intensity and solids content was observed for both. However, this linear relationship was not observed when the particle size distribution of sucrose was changed. It is clear that, especially in the case of many polymorphic conversions, information on the particle size distribution, along with additional structurally sensitive information such as Raman spectra, is essential in gaining a true understanding of the behaviour of the system.

β-CuI nanocrystallites (NCs) are synthesized on the atomically smooth graphite basal plane surface using a new hybrid electrochemical/chemical (E/C) method. This method involves the following steps:  (1) electrochemical deposition of copper NCs onto an electrode surface, (2) electrochemical oxidation of these copper NCs to yield Cu2O, and (3) displacement of oxygen in Cu2O by iodide in an aqueous KI solution. Dispersions of CuI NCs having mean diameters ranging from 10 to 180 Å were prepared using the E/C method. Selected-area electron diffraction analysis reveals that β-CuI NCs are obtained; these NCs are epitaxially aligned with the hexagonal periodicity of the graphite surface, as are the Cu2O precursor particles. For samples of supported CuI NCs having a mean particle height of <25 Å, individual NCs were well-separated from one another on the graphite surface and were narrowly dispersed in height. Photoluminescence spectroscopic analysis showed a strong, room temperature emission at an energy corresponding to the band gap. As the crystallite diameter was reduced from 180 Å to 13 Å, the energy of this emission shifted from the macroscopic value of 2.92 eV to >3.04 eV, in good agreement with the predictions of the effective mass, strong confinement model.