Method and system for measuring the chirality of molecules

Patent metadata

Field	Value
Publication number	US-11404257-B2
Application number	US-201917252185-A
Country	US
Kind code	B2
Filing date	Jun 25, 2019
Priority date	Jun 25, 2018
Publication date	Aug 2, 2022
Grant date	Aug 2, 2022

Abstract

A method for measuring the chirality of molecules in a sample of chiral molecules, the sample including at least one chemical species, the method including the steps of: introducing the sample of chiral molecules into an ionisation area; ionising the molecules by electromagnetic radiation in the ionisation area; and detecting a distribution of electrons produced by ionisation and emitted at the front and back of the ionisation area relative to the axis, z, of propagation of the electromagnetic radiation; wherein the electromagnetic radiation is elliptically polarised, the ellipticity varying continuously and periodically as a function of time, the method further including a step of: determining the chirality of the molecules from the electron distribution detected continuously as a function of time. A system is also provided for measuring the chirality of molecules using such a method.

First claim

The invention claimed is:

1. A method for measuring the chirality of molecules in a sample of chiral molecules, the sample comprising at least one chemical species, wherein the method comprises the following steps:
introducing the sample of chiral molecules into an ionization area;
ionizing the molecules by means of an electromagnetic radiation in the ionization area;
detecting a distribution of electrons produced by the ionization and emitted to the front and to the back of the ionization area with respect to the axis, z, of propagation of the electromagnetic radiation;

the electromagnetic radiation is elliptically polarized, wherein the polarization ellipticity of the radiation varies continuously and periodically as a function of time; and wherein the method includes a step of:
determining the chirality of the molecules from the electron distribution detected continuously as a function of time.

2. The method according to claim 1 , characterized in that the step of determining the chirality is performed in real time.

3. The method according to claim 1 , characterized in that the detection step is carried out through measurements of the number of electrons, emitted to the front and to the back of the ionization area with respect to the axis, z, of propagation of the electromagnetic radiation, at times t i (i=1, 2, etc.), wherein the measured number is integrated during an interval Δt=(t i −t i-1 ) for each measurement.

4. The method according claim 1 , characterized in that the step of determining the chirality of the molecules comprises a step of comparing a number of electrons detected at the front and a number of electrons detected at the back of the ionization area with respect to the axis, z, of propagation of the electromagnetic radiation.

5. The method according to claim 1 , characterized in that it moreover comprises a step of Fourier analyzing a temporal evolution of the electron distribution in order to obtain the frequency spectrum of the distribution.

6. The method according to claim 5 , characterized in that, for a sample of single-specie molecules, the method moreover comprises a step of determining an enantiomeric excess from the frequency spectrum of the electron distribution.

7. The method according to claim 1 , characterized in that it moreover comprises a step of generating a spatial and/or angular distribution map P(x,t) of the emitted electrons from the distribution of the electrons as a function of time t, where x is the position of the electrons on the map.

8. The method according to claim 7 , characterized in that it moreover comprises a step of Fourier analyzing each component of the distribution map.

9. The method according to claim 7 , characterized in that it moreover comprises the following steps:
determining the projection P(z,t) of the distribution map P(x,t) onto the axis, z, of propagation of the electromagnetic radiation; and
Fourier analyzing the temporal evolution of the projection P(z,t) in order to obtain the frequency spectrum.

10. The method according to claim 9 , characterized in that, for a sample of multi-species molecules, the method moreover comprises a step of determining the species of the sample from the frequency spectrum of the projection P(z,t) of the distribution map.

11. The method according to claim 9 , characterized in that the method moreover comprises a step of determining the enantiomeric excess from the frequency spectrum of the projection P(z,t) of the distribution map of the electrons.

12. A system for measuring chirality, comprising:
an ionization area arranged in order to receive a sample of chiral molecules comprising at least one chemical species;
an electromagnetic radiation source arranged in order to emit an electromagnetic radiation and to ionize the chiral molecules in the ionization area by means of the electromagnetic radiation; and
electron detection means arranged in order to detect a distribution of electrons produced by the ionization and emitted to the front and to the back of the ionization area with respect to the axis, z, of propagation of the electromagnetic radiation;
a polarization modulator arranged in order to polarize the electromagnetic radiation elliptically and arranged in order to make the polarization ellipticity of the radiation vary continuously as a function of time; and
a determination device arranged and/or programmed in order to determine the chirality of the molecules from the electron distribution detected continuously as a function of time.

13. The system according to claim 12 , characterized in that the electron detection means comprise at least one of a magnetic field ejection asymmetry detector and a velocity map imaging spectrometer.

14. The system according to claim 12 , characterized in that the electromagnetic radiation source is a laser source.

15. The system according to claim 14 , characterized in that the laser source is a femtosecond pulsed laser source.

16. The system according to claim 15 , characterized in that it moreover comprises a modulator for the duration of the pulses of the laser source.

17. The system according to claim 12 , characterized in that it moreover comprises an ion detector arranged in order to detect the ionized molecules.

18. The system according to claim 17 , characterized in that the ion detector is a mass spectrometer.

19. The system according to claim 12 , characterized in that the polarization modulator comprises a quarter-wave plate arranged in order to be set in rotation about the axis, z, of propagation of the radiation.

20. The system according to claim 12 , characterized in that it moreover comprises an intensity modulator for the electromagnetic radiation and/or a wavelength modulator for the electromagnetic radiation.

21. The system according to claim 12 , characterized in that it is arranged in order to implement a method for measuring the chirality of molecules in a sample of chiral molecules, the sample comprising at least one chemical species, wherein the method comprises the following steps:
introducing the sample of chiral molecules into an ionization area;
ionizing the molecules by means of a electromagnetic radiation in the ionization area;
detecting a distribution of electrons produced by the ionization and emitted to the front and to the back of the ionization area with respect to the axis, z, of propagation of the electromagnetic radiation;

the electromagnetic radiation is elliptically polarized, wherein the polarization ellipticity of the radiation varies continuously and periodically as a function of time; and wherein the method includes a step of determining the chirality of the molecules from the electron distribution detected continuously as a function of time.

Assignees

• Centre Nat Rech Scient
• Univ Bordeaux

Inventors

• Mairesse Yann
• Comby Antoine

Classifications

• H01J49/26

  Mass spectrometers or separator tubes · CPC title

• G01N21/31

  Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry {(G01N21/72 takes precedence)} · CPC title

• H01J49/161

  using photoionisation, e.g. by laser · CPC title

• H01J49/0004

  Imaging particle spectrometry · CPC title

• H01J49/0031 Primary

  Step by step routines describing the use of the apparatus (H01J49/0081 takes precedence) · CPC title