CRASY

Correlated Rotational Alignment Spectroscopy

The PI Mercury™ C-863.10 and PI Mercury™ C-863.11

The PI Mercury™ C-863 is a DC-motor controller which exists in two versions, i.e., the C-863.10 controller and the C-863.11 controller. Both differ in their firmware and their hardware. That makes it difficult to control them using the same software. Here you’ll find some information on how to deal with the new General Command Set of the Mercury™ C-863.11 controller.

How to align a translation stage

Femtosecond spectroscopy uses an ultrashort laser pulse to start a photo-chemical reaction at a well defined moment in time. A second ultrashort laser pulse can be used to visualize the ongoing photo-chemical reaction [1]. To achieve a precise timing between two laser pulses, a laser beam is usually split into two parts. One part of the beam is directed towards the experiment, the second part passes a translation stage before recombination of both beams occurs. By precisely moving the translation stage by a certain distance, the pathway is increased and laser […]

Affordable translation stage for spectroscopy

The translation stage ‘Standa 960-0060’ sells for $399 and offers a full-step resolution of 1.25 micrometer (200 steps/turn, 250 micrometer per turn). With factor 8 or 16 microstepping, the resolution should be sufficient for interferometric experiments with visible light (156 or 78 nm resolution). The stepper can be easily controlled with an Arduino-based USB controller for a cost of less than $40, but a little soldering is required.

Arduino Based Sensors

Problem: We need to track environmental variables in our laboratory to identify parameters that affect our measurement results Solution:  We read out sensors using Arduinos and transfer the sensor data to PCs for storage and analysis. We programmed sensors to analyze temperature, humidity, air pressure, acceleration, and motion. For some sensors (e.g. temperature sensors), the program just involves reading sensor values. For other sensors (e.g., the BMP180 pressure and temperature sensor), a library is required to handle the communication with the sensor. Some programs were written in older Arduino IDEs and they may have to […]

Ask questions like a Pro: Questions you can ask at any scientific seminar

Scientific seminars follow ancient routines. The speaker speaks for his allocated time plus a generous 15% bonus and then the big-shots in the first row ask a few questions. But have you ever noticed that they always ask the same questions? It’s called experience, i.e., they made up their question some 20 years ago. Time for you to get up to speed and participate with your own highly original questions! Don’t have an idea what to ask? Just select one of the generic categories offered  in the PDF file below, […]

Scientific Writing

Writing scientific publications seems to be a science on its own for most of young researchers, but there is no magic behind scientific writing! By following simple rules, everybody can improve his writing skills. I summarized these rules in a cheat sheet for scientific writing. Of course, you should not expect a miracle. Your principal investigator will always find something to complain about. 😉 If you want to read further on The Science of Scientific Writing, please refer to the article.

Ab initio code for starters

Ab initio packages for starters  PCGamess: Ab initio code for your Windows PC  MacMolplt: Nice visualization of Gamess output  Arguslab: Visualize or draw molecules, optimize with molecular dynamics, useful to generate starting geometries  Mopac: Molecular dynamics and semiempirical methods   Suggested sequence for simple structure calculations: (1) Draw your molecule in CHEMSKETCH and push the ‘optimize 3D’ button, save it in .mol format (2) I used OPENBABEL to convert the .mol coordinates to Gamess input format. (3) Perform a PM3 calculation in Gamess Firefly to get a better structure (fast calculation). A […]