Identifying the Mineral Source of Phosphorus-Containing Molecules in Space
Disciplines
Physical Chemistry
Abstract (300 words maximum)
Phosphorous is the only one of the six most abundant elements in life that does not exist in a stable yet volatile form (i.e., as a gas or the vapor of a liquid). Therefore, it must have migrated from a solid mineral into prebiotic molecules. Only a few volatile P-containing species have been observed in space, mainly in the comas of comets or the interstellar medium. Astronomers want to know “What is the reactive P-bearing mineral in these extraterrestrial environments?” We hypothesize that this mineral may be schreibersite or Fe2NiP, a phosphorus-bearing mineral commonly found in iron and stony-iron meteorites, which is known to corrode upon exposure to water under ambient conditions releasing reactive P-bearing compounds. To test this hypothesis, we created a synthetic schreibersite sample and placed it into an ultrahigh vacuum (UHV) experimental chamber with a base pressure of 1.3 x 10-9 torr. A cryohead is used to cool the sample to temperature below 100 K. We dose water (H2O) and methanol (CH3OH, CD3OD) through a variable leak valve and irradiate the surface with a tunable electron gun. To detect structural changes on the surface, we use Reflection-Absorption Infrared Spectroscopy (RAIRS). A quadrupole mass spectrometer (QMS) is used to characterize small molecules and ions desorbing off the surface during the electron irradiation and as the sample is warmed to room temperature. Irradiating with 1000 eV electrons leads to the formation of a new peak in the infrared spectra at 2345 cm-1. This is red-shifted (i.e., shifted to lower frequency and energy) compared to the P-H stretch of phosphite, which is computationally predicted to occur at 2423 cm-1. Therefore, the feature we observe in the RAIRS spectra is more likely CO2, which is expected to have a peak at 2340 cm-1, rather than phosphite on the schreibersite surface.
Academic department under which the project should be listed
CSM - Chemistry and Biochemistry
Primary Investigator (PI) Name
Dr. Abbott-Lyon
Identifying the Mineral Source of Phosphorus-Containing Molecules in Space
Phosphorous is the only one of the six most abundant elements in life that does not exist in a stable yet volatile form (i.e., as a gas or the vapor of a liquid). Therefore, it must have migrated from a solid mineral into prebiotic molecules. Only a few volatile P-containing species have been observed in space, mainly in the comas of comets or the interstellar medium. Astronomers want to know “What is the reactive P-bearing mineral in these extraterrestrial environments?” We hypothesize that this mineral may be schreibersite or Fe2NiP, a phosphorus-bearing mineral commonly found in iron and stony-iron meteorites, which is known to corrode upon exposure to water under ambient conditions releasing reactive P-bearing compounds. To test this hypothesis, we created a synthetic schreibersite sample and placed it into an ultrahigh vacuum (UHV) experimental chamber with a base pressure of 1.3 x 10-9 torr. A cryohead is used to cool the sample to temperature below 100 K. We dose water (H2O) and methanol (CH3OH, CD3OD) through a variable leak valve and irradiate the surface with a tunable electron gun. To detect structural changes on the surface, we use Reflection-Absorption Infrared Spectroscopy (RAIRS). A quadrupole mass spectrometer (QMS) is used to characterize small molecules and ions desorbing off the surface during the electron irradiation and as the sample is warmed to room temperature. Irradiating with 1000 eV electrons leads to the formation of a new peak in the infrared spectra at 2345 cm-1. This is red-shifted (i.e., shifted to lower frequency and energy) compared to the P-H stretch of phosphite, which is computationally predicted to occur at 2423 cm-1. Therefore, the feature we observe in the RAIRS spectra is more likely CO2, which is expected to have a peak at 2340 cm-1, rather than phosphite on the schreibersite surface.