1. Herbst, E. The chemistry of interstellar space. Chem. Soc. Rev. 30, 168–176 (2001).

2. Ospelkaus, S. et al. Quantum-state controlled chemical reactions of ultracold potassium-rubidium molecules. Science 327, 853–857 (2010).

3. Ni, K.-K. et al. Dipolar collisions of polar molecules in the quantum regime. Nature 464, 1324–1328 (2010).

4. Chefdeville, S. et al. Observation of partial wave resonances in low-energy O 2 –H 2 inelastic collisions. Science 341, 1094–1096 (2013).

5. Vogels, S. N. et al. Scattering resonances in bimolecular collisions between NO radicals and H 2 challenge the theoretical gold standard. Nat. Chem. 10, 435–440 (2018).

6. De Marco, L. et al. A degenerate Fermi gas of polar molecules. Science 363, 853–856 (2019).

7. Herschbach, D. R. in Advances in Chemical Physics (ed. Ross, J.) Ch. 9 (Wiley, 1966).

8. Smith, I. W. M. Reactions at very low temperatures: gas kinetics at a new frontier. Angew. Chem. Int. Ed. 45, 2842–2861 (2006).

9. Henson, A. B., Gersten, S., Shagam, Y., Narevicius, J. & Narevicius, E. Observation of resonances in Penning ionization reactions at sub-kelvin temperatures in merged beams. Science 338, 234–238 (2012).

10. Jankunas, J., Bertsche, B., Jachymski, K., Hapka, M. & Osterwalder, A. Dynamics of gas phase Ne∗ + NH 3 and Ne∗ + ND 3 Penning ionisation at low temperatures. J. Chem. Phys. 140, 244302 (2014).

11. Allmendinger, P. et al. New method to study ion–molecule reactions at low temperatures and application to the \({{\rm{H}}}_{2}^{+}+{{\rm{H}}}_{2}\longrightarrow {{\rm{H}}}_{3}^{+}+{\rm{H}}\) reaction. Chem. Phys. Chem. 17, 3596–3608 (2016).

12. Wu, X. et al. A cryofuge for cold-collision experiments with slow polar molecules. Science 358, 645–648 (2017).

13. Greiner, M., Regal, C. A. & Jin, D. S. Emergence of a molecular Bose–Einstein condensate from a Fermi gas. Nature 426, 537–540 (2003).

14. Chin, C. et al. Observation of Feshbach-like resonances in collisions between ultracold molecules. Phys. Rev. Lett. 94, 123201 (2005).

15. Takekoshi, T. et al. Ultracold dense samples of dipolar RbCs molecules in the rovibrational and hyperfine ground state. Phys. Rev. Lett. 113, 205301 (2014).

16. Rvachov, T. M. et al. Long-lived ultracold molecules with electric and magnetic dipole moments. Phys. Rev. Lett. 119, 143001 (2017).

17. Ye, X., Guo, M., González-Martínez, M. L., Quéméner, G. & Wang, D. Collisions of ultracold 23Na87Rb molecules with controlled chemical reactivities. Sci. Adv. 4, eaaq0083 (2018).

18. Barry, J. F., McCarron, D. J., Norrgard, E. B., Steinecker, M. H. & DeMille, D. Magneto-optical trapping of a diatomic molecule. Nature 512, 286–289 (2014).

19. Truppe, S. et al. Molecules cooled below the Doppler limit. Nat. Phys. 13, 1173–1176 (2017).

20. Kozyryev, I. et al. Sisyphus laser cooling of a polyatomic molecule. Phys. Rev. Lett. 118, 173201 (2017).

21. Anderegg, L. et al. Radio frequency magneto-optical trapping of CaF with high density. Phys. Rev. Lett. 119, 103201 (2017).

22. Anderegg, L. et al. An optical tweezer array of ultracold molecules. Preprint at https://arxiv.org/abs/1902.00497 (2019).

23. Weinstein, J. D., deCarvalho, R., Guillet, T., Friedrich, B. & Doyle, J. M. Magnetic trapping of calcium monohydride molecules at millikelvin temperatures. Nature 395, 148–150 (1998).

24. Bethlem, H. L. et al. Electrostatic trapping of ammonia molecules. Nature 406, 491–494 (2000).

25. van de Meerakker, S. Y. T., Smeets, P. H. M., Vanhaecke, N., Jongma, R. T. & Meijer, G. Deceleration and electrostatic trapping of OH radicals. Phys. Rev. Lett. 94, 023004 (2005).

26. Haas, D., von Planta, C., Kierspel, T., Zhang, D. & Willitsch, S. Long-term trapping of cold polar molecules. https://arxiv.org/abs/1904.00713 (2019).

27. Hoekstra, S. et al. Optical pumping of trapped neutral molecules by blackbody radiation. Phys. Rev. Lett. 98, 133001 (2007).

28. Hoekstra, S. et al. Electrostatic trapping of metastable NH molecules. Phys. Rev. A 76, 063408 (2007).

29. Zeppenfeld, M. et al. Sisyphus cooling of electrically trapped polyatomic molecules. Nature 491, 570–573 (2012).

30. Liu, Y. et al. Magnetic trapping of cold methyl radicals. Phys. Rev. Lett. 118, 093201 (2017).

31. Parazzoli, L. P., Fitch, N. J., Z˙uchowski, P. S., Hutson, J. M. & Lewandowski, H. J. Large effects of electric fields on atom–molecule collisions at millikelvin temperatures. Phys. Rev. Lett. 106, 193201 (2011).

32. Hummon, M. T. et al. Cold N+NH collisions in a magnetic trap. Phys. Rev. Lett. 106, 053201 (2011).

33. Singh, V. et al. Chemical reactions of atomic lithium and molecular calcium monohydride at 1 K. Phys. Rev. Lett. 108, 203201 (2012).

34. Stuhl, B. K. et al. Evaporative cooling of the dipolar hydroxyl radical. Nature 492, 396–400 (2012).

35. Reens, D., Wu, H., Langen, T. & Ye, J. Controlling spin flips of molecules in an electromagnetic trap. Phys. Rev. A 96, 063420 (2017).

36. Ketterle, W. & Van Druten, N. J. Evaporative cooling of trapped atoms. Adv. At. Mol. Opt. Phys. 37, 181–236 (1996).

37. Hess, H. F. et al. Magnetic trapping of spin-polarized atomic hydrogen. Phys. Rev. Lett. 59, 672–675 (1987).

38. Akerman, N. et al. Simultaneous deceleration of atoms and molecules in a supersonic beam. New J. Phys. 17, 065015 (2015).

39. Akerman, N. et al. Trapping of molecular oxygen together with lithium atoms. Phys. Rev. Lett. 119, 073204 (2017).

40. Yokelson, R. J., Lipert, R. J. & Chupka, W. A. Identification of the nsσ and ndλ Rydberg states of O 2 for n = 3–5. J. Chem. Phys. 97, 6153–6167 (1992).

41. Avdeenkov, A. V. & Bohn, J. L. Ultracold collisions of oxygen molecules. Phys. Rev. A 64, 052703 (2001).

42. Bird, G. A. Molecular Gas Dynamics and the Direct Simulation of Gas Flows (Clarendon Press, 1994).

43. Geppert, W. D. et al. Comparison of the cross-sections and thermal rate constants for the reactions of C(3P J ) atoms with O 2 and NO. Phys. Chem. Chem. Phys. 2, 2873–2881 (2000).

44. Tscherbul, T. V., Suleimanov, Y. V., Aquilanti, V. & Krems, R. V. Magnetic field modification of ultracold molecule–molecule collisions. New J. Phys. 11, 055021 (2009).

45. Pérez-Ríos, J., Campos-Martínez, J. & Hernández, M. I. Ultracold O 2 + O 2 collisions in a magnetic field: on the role of the potential energy surface. J. Chem. Phys. 134, 124310 (2011).

46. Even, U. The Even–Lavie valve as a source for high intensity supersonic beam. EPJ Tech. Instrum. 2, 17 (2015).

47. Even, U., Jortner, J., Noy, D., Lavie, N. & Cossart-Magos, C. Cooling of large molecules below 1 K and He clusters formation. J. Chem. Phys. 112, 8068–8071 (2000).