CRASY data

posted on 14.02.2018 by Thomas Schultz, Jong Chan Lee, Christian Schröter
CRASY data description, data-sets, and data analysis guide.

The data-sets correspond to the continuously sampled data and sparsely sampled data show in the manuscript "Mass-correlated Rotational Raman Spectra with High Resolution, Broad Bandwidth, and Absolute Frequency Accuracy" (to be published).

Data-sets contain mass-CRASY data (zipped):
- Oct14_09.54-short (short data sample for testing)
- Aug11_20.57 (continuous sampling data)
- Dec16_20.15 (sparse sampling data)

Refer to the CRASY data format description to understand the data file contents.

Refer to the Python script to see an example of how the data can be accessed.

Contact the authors if you require further information.
Introduction of CRASY
To understand the nature of CRASY measurements, refer to [Schroter C, Kosma K, Schultz T (2011) Crasy: Mass- or electron-correlated rotational alignment spectroscopy. Science 333:1011-1015.]
CRASY data consists of spectroscopic data (spectroscopic axis 1, e.g., photoionization mass spectra), measured as function of delay time relative to the excitation of a rotational wave packet. Signal modulations due to the wavepacket evolution contain information about rotational transitions encoded in the wave packet. Fourier-transformation of the signal modulations reveal rotational spectra (spectroscopic axis 2) that are inherently tied to the observed properties along spectroscopic axis 1.

CRASY data format description
A CRASY data-set consists of multiple files stored in a directory or zip file. Filenames denote the file content. I use Regex expressions to specify the information encoded in the filenames:
TS_[\s]+\d: measurement number \d (incrementing for each delay step)
*r\d*: repeat number \d (only relevant for sequential scans)
*w\d*: label for alignment signal (w1) and unaligned reference signal (w2)
(only present in scans measuring unaligned reference signal)

*.hdr files hold header information:
Line 1: Data acquisition program name
Line 2: Current delay time in ps
[Note the delay stage is: Physik Instrumente, MD-531, 16x folded beam path]
Line 3: Number of laser shots (signal was summed for this n.o.l.s.)
Line 5: Date and time of measurement start
Line 6,7: Obsolete detector parameters
Line 8: Digitizer time-of-flight acquisistion delay (in ns)
Line 9: Digitizer time-of-flight acquisition range (in ns)
[Note: The digitizer is a Fast Comtech 7886 card, the actual acquisition range is not identical to the set range. The acquisition bin width is 500 ps.]
Line 10-12: Obsolete scan and calibration parameters
Line 13-19: Environmental parameters
Line 21,22: Motorized laser mirror position (tracking of molecular beam)
Line 23: Number _n_ of oscillator jumps (delay += n/Osc_freq for each)
Line 24: Oscillator frequency

*.int files hold spectra (e.g., time-of-fligh mass spectra):
First 10 bytes denote the size (bytes) of the inflated spectrum.
The remaining data contains the spectrum in zlib compressed format, 16-bit bins.
Inflate using zlib library (https://www.zlib.net/; function 'uncompress'), or zlib.decompress in Python.


National Research Foundation of Korea, NRF-2014R1A2A1A11053055