We have used laser ablation and helium buffer-gas cooling to produce the titanium-helium van der Waals molecule at cryogenic temperatures. The molecules were detected through laser-induced fluorescence spectroscopy. Ground-state Ti(a 3 F2)-He binding energies were determined for the ground and first rotationally excited states from studying equilibrium thermodynamic properties, and found to agree well with theoretical calculations based on newly calculated ab initio Ti-He interaction potentials, opening up novel possibilities for studying the formation, dynamics, and non-universal chemistry of van der Waals clusters at low temperatures.PACS numbers: 34.50. Lf, 33.15.Fm, Weakly bound complexes of atoms and molecules held together by long-range van der Waals (vdW) forces are key to understanding a wide range of phenomena in physics and chemistry, ranging from classical and quantum chaos [1] and phase transitions [2] to the universal physics of Efimov trimers and quantum droplets [3][4][5]. In condensed-phase chemical physics, vdW clusters serve as a model to study the mechanisms of solvation, nucleation, and chemical reactivity [6][7][8]. In the context of quantum many-body physics, vdW molecules can be used to explore the formation of exotic quasiparticles in superfluid helium nanodroplets [9]. Helium-containing vdW molecules are the lightest of all vdW clusters, and hence are of particular interest as model systems, in which to study the emergence of macroscopic quantum phenomena such as superfluidity [10].Thus far, the experimental study of He-containing vdW molecules has focused on molecules formed in supersonic expansions [8,[11][12][13][14][15]. Recent groundbreaking advances in the production and trapping of translationally cold molecules [16] made it possible to create trapped ensembles of cold polar molecules with high enough densities to study collisions and chemical reactions [16][17][18] and carry out ultra-precise spectroscopic measurements to probe the physics beyond the Standard Model [19]. The production and trapping of cold vdW molecules would similarly enable highly sensitive spectroscopic detection of heretofore unobserved clusters, as well as the study and control of their quantum dynamics [7,[20][21][22].We have recently observed the formation of cold, ground-state LiHe molecules in a cryogenic He buffer gas [23]. The LiHe molecule has a single near-threshold bound state with a binding energy of 0.024 cm −1 [24] comparable to that of the He 2 dimer [11,21]. Due to their vanishingly small binding energies, these molecules belong to an exotic class of quantum halo dimers characterized by extremely delocalized wavefunctions, universal properties, and enormously large three-body formation rates [3,25]. As the binding energies of most other * weinstein@physics.unr.edu; http://www.physics.unr.edu/xap/ atoms and molecules with He are much larger than those of LiHe and He 2 [7], it is far from obvious whether atomHe vdW clusters would form upon immersing the parent atoms into cryogenic He buffer gas. ...