再论含金硫化物矿物中能否存在负价金问题──答李九玲等同志

本文从讨论金属结合能何以具有表面化学位移的原因开始,从金属团簇的一般性质出发,论证了金属结合能自尺寸大于1nm的团簇到金属微粒再到块体金属具有连续过渡性;金属结合能与粒径R呈正相关;与1／R具线性负相关关系,认为金微粒或团簇具有1．1eV以上的结合能负位移是可能的。并指出李九玲等同志在“评<含金硫化物矿物中不可能存在负价金>”一文中引用的某些衬底材料上的金团簇呈现结合能正位移的数据是由于这些金困簇已与其衬底材料发生了键合作用造成的,它们不能作为否定金属结合能位移与粒径呈正相关的依据。同时,笔者从“化学结合金”在氰化过程中并未被氧化成正离子金判断,它不应是负价金。并由同质并能位移与粒径可具负相关关系推论,“化学结合金”应是合企硫化物矿物中可存在的少量微粒碲金矿、碲金银矿等中的正离子金。笔者强调在讨论企的价态问题时应采用Allred－Rochow电负性数据而非常用的Pauling电负性数据,并再次指出含金硫化物矿物中不可能有负价金存在。

A FURTHER DISCUSSION ON WHETHER THERE EXISTS NEGATIVE-VALENCE GOLD IN Au-BEARING SULFIDES-A REPLY TO LI JIULING ET AL

From the general characters of metal-clusters and the mechanism of surface core-level shift of met-al binding enerey, the authors demonstrate that the metal binding energy is of continuous transitionfrom metal-clusters measuring about 1 nm in radius to metal-particles, then to metal blocks in this pa-per. It is also demonstrated that there is a directly proportional relationship between the metal bindingenergy and the radius (R) of metal particles, and there is a linear negative correlation between themetal binding energy and 1/R. The authors believe that the binding energy negative shift of gold par-ticles or gold clusters may be larger than 1. 1 eV.The authors indicate that the direct data on the binding enefgy shift of some god clusters whichare supported on carbon, SiO2, Al2O3, etc., cited by Li Jiuling et al. in the paper "Comment on' NoNegative-valence Gold in Au-bearing Sulfide-A Discussion with Wang Yuming et al.'" is due to thefact that these gold clusters are combined with their supporting materials. These data cannot be re-garded as the basis for negating the directly proportional relationship between the binding energy shiftand the radius of metal. Meanwhile, the authors believe that the "combined gold" cannot be the nega-tive-valence gold because it had not been oxidized in the course of cyaniding. It is inferred that the"combined gold" may be the gold cation in gold-telluride mineral particles which must exist in Au-bear-ing sulfides. The authors stress that the data on Allred-Rochow electronegativity should be employedinstead of the data on Pauling electronegativity, especially in the discussion of the valence of gold. Theauthors conclude that there is no negative-valence gold in the Au-bearing sulfides.