Thermodynamic investigation of the lead molecules Pb2, Pb3, and Pb4 by mass spectrometry

Abstract

The high-temperature Knudsen effusion mass spectrometric technique has been used to determine the thermodynamic properties of the molecules Pb2, Pb3, and Pb4. The enthalpies of the following reactions were determined: nPb(s,l) =Pbn(g), Pb(s,l)+Pbn−1(g) = Pbn(g), and Pbn(g) =nPb(g). From the values obtained and appropriate literature data the following atomization energies D°298 and standard heats of formation ΔH°f,298, in kJ per mole, were obtained: Pb2, 81±6 and 310±6; Pb3, 224±16 and 360±16; and Pb4, 408±16 and 372±16.

Metastability ofPbn2+clusters: Role of correlation effects

“…(l)-(3)] by comparing our results for a few small clusters with available experiments and first-principles calculations, e.g., configuration interaction (CI) or local-spin-density (LSD) methods. Our result for the binding energy Et of Pb3 (Eb =2.4 eV) compares well with the experimental value (£.^expt^2.3 eV [13]). In agreement with quantum chemical calculations and experimental evidence we obtain that Ara"^ has a linear geometry and a binding energy Et=0.24 eV (^6^^^=0.18 eV [14], ^^^^^^=0.22 eV [15]).…”

“…6 eV are obtained from the first and second ionization potentials of the lead atom. The hopping integrals tppa==lA eV and /^p;,= ~0.08 eV and the Born-Mayer parameters A =0,9 eV and K-= 10.5 are fitted to the experimental binding energy, equilibrium distance Ro=3A7 A, and vibrational frequency of the neutral dimer [13]. In this way realistic parameters are obtained which guarantee that the fundamental Pb-Pb bond is properly described.…”

Investigation of the stabilities of neutral and ionic lead and lead-antimony clusters under single and multiphoton ionization conditions

“…The strong dependence of the cluster distribution on laser fluence observed at 222 nm undoubtedly re- From [20] u From [24] Calculated from the data in [24] flects the effect of a change from single photon to multiphoton ionization conditions. The proportionately greater number of larger clusters observed at low fluence emphasizes the lower contribution from fragmentation compared to high fluence, multiphoton ionization conditions.…”

Geometric structures and dipole moments of Pbn (n=13–18) clusters from ab initio quantum-chemical calculations

“…For Pb 15 , an extensive structural search is performed, among 29 numerous possible structural isomers six types of structures are obtained as shown in Fig. 1.…”

“…Over the last decade, the structures and electronic properties of 14 group elements clusters have been an area of intense investigation [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], because of their fundamental interest and potential application in nanotechnology. Much attention has been focused on understanding the structural and physicochemical properties of Si, Ge, Sn, and Pb clusters since the discovery of highly stable C 60 [21].…”