Synthesis of size and shape-selective Au nanocrystals via proton beam irradiation Yeong-Joon Kim a , Gyoujin Cho b , Jae Hee Song c, * a Department of Chemistry, Chungnam National University, Daejeon 305-764, Republic of Korea b Department of Chemical Engineering, Sunchon National University, Suncheon 540-742, Republic of Korea c Department of Chemistry, Sunchon National University, 315 Maegok, Suncheon 540-742, Republic of Korea Received 5 December 2005; received in revised form 23 December 2005 Available online 14 February 2006 Abstract We describe a synthetic route for the high yield production of Au nanomaterials via a simple proton beam irradiation process. Size and shape-controlled Au nanocrystals were prepared by just varying the ion current and the duration of irradiation. It was observed that the size of the prepared gold nanocrystals was reduced significantly as the ion current was increased for the same irradiation time. Fur- thermore, we were able to fabricate gold nanorods by using proton beam irradiation in the presence of silver ions, which is known to be critical for the one-dimensional growth of gold nanorods. Ó 2006 Elsevier B.V. All rights reserved. PACS: 82.70.Dd; 81.07.Bc; 81.07.b Keywords: Proton beam irradiation; Gold; Nanocrystals; Nanorods 1. Introduction It is well known that nanosized Au crystals differ greatly in their physical and chemical properties from the bulk material and the Au element, and the properties of Au nanomaterials are critically dependent not only on particle size but on particle shape as well [1–3]. Hence, the synthesis and characterization of nanosized materials is an impor- tant issue in basic science research as well as in technolog- ical applications. Therefore, a considerable research effort has been focused on size and shape-selective nanocrystal growth using a variety of synthetic methods, including elec- trochemistry [4], templating [5–7], photochemistry [8,9] and seeding [10–12]. Recently it has been reported that the fab- rication of thiol-stabilized monodispersed gold nanoparti- cles was achieved through electron beam irradiation of gold(I) complex [13]. More recently, surfactant-free synthe- sis of gold nanoparticles with a good control over particle size and with narrow dispersity has been reported [14]. Recently, we found out that proton beam irradiation can be used as a powerful alternative reducing source for the facile synthesis of gold nanoparticles. Although proton beams have been utilized for many applications [15–18], such as BT, IT, NT, ST, ET and medical purposes, it has not been directly used for the preparation of well defined metal nanostructures. In this study, we describe a synthetic route for the high yield production of Au nanomaterials via a simple proton beam irradiation process. Size and shape- controlled Au nanocrystals were prepared by just varying the ion current and the duration of irradiation. To our knowledge, this is the first example utilizing proton beam irradiation for the facile synthesis of Au nanoparticles. Furthermore, we were able to fabricate gold nanorods by using proton beam irradiation in the presence of silver ions, which is known to be critical for the one-dimensional 0168-583X/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2006.01.005 * Corresponding author. Tel.: +82 61 750 3631; fax: +82 61 750 3608. E-mail address: j1song@sunchon.ac.kr (J.H. Song). www.elsevier.com/locate/nimb Nuclear Instruments and Methods in Physics Research B 246 (2006) 351–354 NIM B Beam Interactions with Materials & Atoms