Sequential infiltration synthesis

Sequential infiltration synthesis (SIS) is a technique derived from atomic layer deposition (ALD) in which a polymer is infused with inorganic material using sequential, self-limiting exposures to gaseous precursors, allowing precise control over the composition, structure, and properties of product materials.[1][2][3][4][5][6][7]

This synthesis involves metal-organic vapor-phase precursors and co-reactants dissolving and diffusing into polymers, interacting with the functional groups on the polymers via reversible complex formation and/or irreversible chemical reactions, and yielding desired composite materials, which may be nanostructured. The metal-organic precursor (A) and co-reactant vapor (B) are supplied in an alternating ABAB sequence. Following SIS, the organic phase may be removed thermally or chemically to leave only the inorganic components behind. The control SIS provides over infiltration and synthesis enables the fabrication of materials with desired properties such as specific composition, mechanics, stoichiometry, porosity, conductivity, refractive index, and chemical functionality on the nanoscale.[8]

SIS has been applied in various fields, including electronics, energy storage, AI and catalysis, due to its capacity for material property modification. SIS is sometimes referred to as "multiple pulsed vapor-phase infiltration" (MPI),[9] "vapor phase infiltration" (VPI)[10] or "sequential vapor infiltration" (SVI).[11]

SIS involves the 3D distribution of functional groups in polymers, while its predecessor, ALD, is associated with the impermeable 2D distribution of reactive sites on solid surfaces. In SIS, the partial pressures and exposure times for the precursor pulse are typically larger compared to ALD to allow for a sufficient amount of precursor to infiltrate the 3D volume by dissolution and diffusion.[1] SIS utilizes the diffusive nature of precursor transport within polymers, making the distribution of precursors within the material sensitive to time, pressure, temperature, polymer chemistry, and micro-structure.[1]

History

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The diffusion of precursors below the surfaces of polymers during ALD was observed in 2005 by the Steven M. George group when they observed that polymers could uptake trimethylaluminium (TMA) via absorption within their free volume.[12] In the study, the interactions between the ALD precursors and the polymer functional groups were not recognized, and the diffusion of precursors into polymer films was considered a problem. Hence, the diffusion and reactions of ALD precursors into polymer films were considered challenges to address rather than opportunities. However, potential benefits of these phenomena were demonstrated by Knez and coworkers in a 2009 report describing the increased toughness of spider silk following vapor-phase infiltration.[9]

Sequential infiltration synthesis was developed by Argonne National Laboratory scientists Jeffrey Elam and Seth Darling in 2010 to synthesize nanoscopic materials starting from block copolymer templates.[13] A patent application was filed in 2011 and the first patent was issued in 2016.[14] SIS involves vapour diffusing into an existing polymer and chemically or physically binding to it. This results in the growth and formation of inorganic structures by selective nucleation throughout the bulk polymer.

With SIS, the shapes of various inorganic materials can be tailored by applying their precursor chemistries to patterned or nano-structured organic polymers, such as block copolymers.[15] SIS was developed to intentionally enable the infusion of inorganic materials such as metal oxides and metals within polymers to yield hybrid materials with enhanced properties. Hybrid materials created via SIS can further be subjected to thermal annealing steps to remove the polymer constituents entirely to derive purely inorganic materials that maintain the structure of the original polymer morphology, including mesoporosity.[16]

Although the early research in SIS focused on a small number of inorganic materials such as Al2O3, TiO2, and ZnO, the technology diversified over the next decade and came to include a wide variety of both inorganic materials and organic polymers, as detailed in reviews.[1][2][3][4][5][6][7]

Principles and process

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SIS is based on the consecutive introduction of different precursors into a polymer, taking advantage of the material's porosity on the molecular scale. This allows the precursors to diffuse into the material and react with specific functional groups located along the polymer backbone or pendant group. [17][18] Through the selection and combination of the precursors, a rich variety of materials can be synthesized, each of which can endow unique properties to the material.[19][20][21]

The process of SIS involves various key steps, the first of which is materials selection. A suitable substrate material, such as a polymer film, and precursors, typically molecules that can react with the substrate's functional groups, are used for the infiltration synthesis. The pairing of polymer chemistry and precursor species is vital for acquiring the desired functionalization and modification.[3]

The substrate is placed in a reactor with an inert atmosphere (typically an inert gas or vacuum). The first precursor vapor (e.g., trimethylaluminum, TMA) is introduced at a sufficiently high vapor pressure and duration such that the precursor molecules diffuse into the substrate.[1] Thus the precursor infiltrates the material and then reacts with the interior functional groups.

After a suitable diffusion/reaction time, the reactor is purged with inert gas or evacuated to remove reaction byproducts and un-reacted precursors. A second vapor-phase species, often a co-reactant, such as H2O, is introduced. Again, the precursor partial pressure and exposure time are selected to allow sufficient time and thermodynamic driving force for diffusion into the polymer and reaction with the functional groups left by the first precursor exposure.[1] The second precursor is then purged or evacuated to complete the first SIS cycle.

The second precursor may also introduce new functional groups that react with the first precursor during subsequent SIS cycles. Sequential infiltration steps can then be repeated, either with the same precursor species or with different ones, until the desired material modifications are achieved. Once the necessary infiltrations are complete, the modified material can undergo additional post-treatment steps to further enhance the properties of the modified layers, such as improving their stability. These post-treatment processes may include heating, chemical treatments, or oxidation to eliminate the organic polymer.[6][7]

With SIS it is natural to apply to block copolymer substrates.[13][3] Block copolymers such as polystyrene-block-poly(methyl methacrylate), PS-b-PMMA, can spontaneously undergo microphase separation to form a rich variety of periodic mesoscale patterns. If the SIS precursors are selected to react with just one of the BCP components but not with the second component, then the inorganic material will only nucleate and grow in that component. For instance, TMA will react with the PMMA side chains of PS-b-PMMA but not with the PS side chains. Consequently, SIS using TMA and H2O as precursor vapors to infiltrate a PS-b-PMMA microphase-separated substrate will form Al2O3 specifically in the PMMA-enriched microphase subdomains. Subsequent removal of the PS-b-PMMA by using oxygen plasma or by annealing in air will convert the combined organic and inorganic mesoscale pattern into a purely inorganic Al2O3 pattern that shares the mesoscale structure of the block copolymer but is more chemically and thermally robust.

Applications

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The capability of SIS to modify polymeric materials in a controlled manner has resulted in utility across a range of technology sectors.

Lithography

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One of the main applications of SIS is in the enhancement of etch resistance in lithographic photoresist, such as those used in photolithography, microfabrication, and nanolithography. This method involves the sequential deposition of inorganic materials within a patterned resist's micro/nanostructures. By carefully controlling the infiltration of these materials, SIS can precisely engineer the chemical composition and density of the resist, thus enhancing its resistance to common etching processes. This enables technologists to achieve finer feature patterns and increased durability in microfabrication, ultimately advancing the capabilities of semiconductor manufacturing and nanotechnology applications. Another recent application for SIS in lithography is to enhance the optical absorption of the photoresist in the extreme ultraviolet range[22] to improve EUV lithography.

Surface coatings

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SIS has applications in the field of surface coatings, particularly in the development of coatings with specific functional properties. With the sequential infiltration of different precursors into the material, SIS allows for the creation of coatings with enhanced properties and performance such as durability, corrosion resistance, oleophilicity[23][24]/lipophilicity, anti-reflection,[25] and/or improved adhesion to substrates. Such an application of SIS can be used for protective coatings for metals, anti-fouling coatings for biomedical applications, and coatings for optical and electronic devices.[26][27][28] In this application, the diffusion and reaction of the SIS precursors below the polymer surface facilitate a bulk-like transformation such that the effective thickness of the surface coating (e.g., several microns) is much larger than the film thickness that would result using the same number of atomic layer deposition (ALD) cycles on a conventional, dense substrate (e.g., a few nanometers).

Sensors and actuators

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SIS, with its precise control over material properties, can be used to develop sensors and actuators.[29][30] The functional layers created through the selective infiltration of specific precursors can enhance the sensitivity, selectivity, and response of sensors, which have applications in gas sensing, chemical sensing, biosensing, and environmental monitoring. SIS is also promising when used to engineer actuators with tunable properties, enabling the fabrication of devices on micro- and nanoscales for various applications.

Energy devices

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SIS has also shown promise in energy devices, especially in improving the performance and stability of energy storage and conversion systems. Employing SIS and the correct precursors, the technique can modify the surfaces and interfaces of materials used in batteries, super-capacitors, and fuel cells, enhancing charge transport, electrochemical stability, and energy density. SIS is also being explored for its applications in photovoltaics,[31] in which it can be used to engineer interfaces and increase light absorption.

Biomedicine

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SIS is a tool for surface modifications to improve biocompatibility, bioactivity, and controlled drug release, making it useful in some biomedical applications. Polymers and bioactive macro-molecules treated with SIS can obtain coatings with developed cell adhesion and reduced bacterial adhesion, as well as provide a medium for the controlled release of therapeutics. Such properties are applicable in biomedicine, such as implantable medical devices, tissue engineering, and drug delivery systems.

Biomaterials

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Modification of the mechanical properties of proteins is an early example of SIS application. For Spider dragline silk the toughness characteristic was significantly enhanced when metallic impurities Titanium or Aluminum were infiltrated in to the fibers. This fiber doping using SIS techniques attempts to mimic the effect of metallic impurities on silk properties observed in nature.[9]

Advantages and limitations

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As the advantages and disadvantages of SIS are outlined, it is important to note that the advantages and limitations of SIS are continually being explored, addressed, and improved upon as research and development efforts in the field are currently ongoing.

Advantages

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SIS allows for precise control over the composition, structure, and properties of materials. The sequential nature of the synthesis process enables the integration of multiple materials and the creation of complex and multi-functional nanostructures. SIS enables atomic-level precision in controlling the deposition of precursor materials. This high level of precision allows creating nanostructures with uniform dimensions, well-defined interfaces, and tailored properties.

SIS is a highly versatile fabrication technique compatible with a wide variety of polymer chemistries and precursor species. By carefully selecting specific precursor materials, researchers can tailor the properties of the resulting fabricated materials, such as electrical conductivity, optical characteristics, and catalytic activity. This flexibility enables a broad spectrum of applications, including electronics, photonics, energy devices, separation technologies, and beyond.

Limitations

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One of the main challenges of SIS is the need to perform the process in an inert environment. Creation of a vacuum and/or introduction of inert gas carries costs that may be prohibitive for applications.

A second challenge lies in the inherent complexity of the diffusion-reaction process. The specifics of reactor configuration and process parameters significantly influence the final material properties, complicating process optimization, reproducibility, and scalability. While SIS is versatile and applicable to a broad range of materials, not all materials are compatible with this technique. The relatively slow diffusion rate of SIS precursor vapors through polymers can make the process time-intensive, particularly over macroscopic distances. For example, infiltrating millimeter-scale depths into a polymer may necessitate precursor exposure times of several hours. For comparison, ALD of thin films on dense surfaces that do not involve diffusion into the substrate would require exposure times of <1 s using the same precursors.[1]

References

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  1. ^ a b c d e f g Waldman, Ruben Z.; Mandia, David J.; Yanguas-Gil, Angel; Martinson, Alex B. F.; Elam, Jeffrey W.; Darling, Seth B. (2019-11-21). "The chemical physics of sequential infiltration synthesis—A thermodynamic and kinetic perspective". The Journal of Chemical Physics. 151 (19). Bibcode:2019JChPh.151s0901W. doi:10.1063/1.5128108. ISSN 0021-9606. PMID 31757164.
  2. ^ a b Elam, Jeffrey W; Biswas, Mahua; Darling, Seth; Yanguas-Gil, Angel; Emery, Jonathan D.; Martinson, Alex B. F.; Nealey, Paul F.; Segal-Peretz, Tamar; Peng, Qing; Winterstein, Jonathan; Liddle, J. Alexander; Tseng, Yu-Chih (2015-09-10). "New Insights into Sequential Infiltration Synthesis". ECS Transactions. 69 (7): 147–157. Bibcode:2015ECSTr..69g.147E. doi:10.1149/06907.0147ecst. ISSN 1938-5862. PMC 5424714. PMID 28503252.
  3. ^ a b c d Leng, Collen Z.; Losego, Mark D. (2017). "Vapor phase infiltration (VPI) for transforming polymers into organic–inorganic hybrid materials: a critical review of current progress and future challenges". Materials Horizons. 4 (5): 747–771. doi:10.1039/C7MH00196G. ISSN 2051-6347.
  4. ^ a b Weisbord, Inbal; Shomrat, Neta; Azoulay, Rotem; Kaushansky, Alexander; Segal-Peretz, Tamar (2020-06-09). "Understanding and Controlling Polymer–Organometallic Precursor Interactions in Sequential Infiltration Synthesis". Chemistry of Materials. 32 (11): 4499–4508. doi:10.1021/acs.chemmater.0c00026. ISSN 0897-4756.
  5. ^ a b Parsons, Gregory N.; Atanasov, Sarah E.; Dandley, Erinn C.; Devine, Christina K.; Gong, Bo; Jur, Jesse S.; Lee, Kyoungmi; Oldham, Christopher J.; Peng, Qing; Spagnola, Joseph C.; Williams, Philip S. (December 2013). "Mechanisms and reactions during atomic layer deposition on polymers". Coordination Chemistry Reviews. 257 (23–24): 3323–3331. doi:10.1016/j.ccr.2013.07.001.
  6. ^ a b c Subramanian, Ashwanth; Tiwale, Nikhil; Nam, Chang-Yong (January 2019). "Review of Recent Advances in Applications of Vapor-Phase Material Infiltration Based on Atomic Layer Deposition". JOM. 71 (1): 185–196. Bibcode:2019JOM....71a.185S. doi:10.1007/s11837-018-3141-4. ISSN 1047-4838. OSTI 1491681. S2CID 255400603.
  7. ^ a b c Azpitarte, Itxasne; Knez, Mato (September 2018). "Vapor phase infiltration: from a bioinspired process to technologic application, a prospective review". MRS Communications. 8 (3): 727–741. doi:10.1557/mrc.2018.126. ISSN 2159-6859. S2CID 104530697.
  8. ^ Tseng, Yu-Chih; Mane, Anil U.; Elam, Jeffrey W.; Darling, Seth B. (2012-05-15). "Enhanced Lithographic Imaging Layer Meets Semiconductor Manufacturing Specification a Decade Early". Advanced Materials. 24 (19): 2608–2613. Bibcode:2012AdM....24.2608T. doi:10.1002/adma.201104871. PMID 22488639. S2CID 36560875.
  9. ^ a b c Lee, Seung-Mo; Pippel, Eckhard; Gösele, Ulrich; Dresbach, Christian; Qin, Yong; Chandran, C. Vinod; Bräuniger, Thomas; Hause, Gerd; Knez, Mato (2009-04-24). "Greatly Increased Toughness of Infiltrated Spider Silk". Science. 324 (5926): 488–492. Bibcode:2009Sci...324..488L. doi:10.1126/science.1168162. ISSN 0036-8075. PMID 19390040. S2CID 5997001.
  10. ^ McGuinness, Emily K.; Zhang, Fengyi; Ma, Yao; Lively, Ryan P.; Losego, Mark D. (2019-07-18). "Vapor Phase Infiltration of Metal Oxides into Nanoporous Polymers for Organic Solvent Separation Membranes". Chemistry of Materials. 31 (15): 5509–5518. doi:10.1021/acs.chemmater.9b01141. ISSN 0897-4756. S2CID 199069476.
  11. ^ Dandley, Erinn C.; Needham, Craig D.; Williams, Philip S.; Brozena, Alexandra H.; Oldham, Christopher J.; Parsons, Gregory N. (2014-10-23). "Temperature-dependent reaction between trimethylaluminum and poly(methyl methacrylate) during sequential vapor infiltration: experimental and ab initio analysis". Journal of Materials Chemistry C. 2 (44): 9416–9424. doi:10.1039/C4TC01293C. ISSN 2050-7534.
  12. ^ Wilson, C. A.; Grubbs, R. K.; George, S. M. (2005-11-01). "Nucleation and Growth during Al 2 O 3 Atomic Layer Deposition on Polymers". Chemistry of Materials. 17 (23): 5625–5634. doi:10.1021/cm050704d. ISSN 0897-4756.
  13. ^ a b Peng, Qing; Tseng, Yu-Chih; Darling, Seth B.; Elam, Jeffrey W. (2011-06-28). "A Route to Nanoscopic Materials via Sequential Infiltration Synthesis on Block Copolymer Templates". ACS Nano. 5 (6): 4600–4606. doi:10.1021/nn2003234. ISSN 1936-0851. PMID 21545142.
  14. ^ US 9487600, issued 2016-11-8 
  15. ^ "Tracking the Early Stages of Sequential Infiltration Synthesis | Advanced Photon Source". www.aps.anl.gov. 2021-03-16. Retrieved 2023-07-25.
  16. ^ Gong, Bo; Peng, Qing; Jur, Jesse S.; Devine, Christina K.; Lee, Kyoungmi; Parsons, Gregory N. (2011-08-09). "Sequential Vapor Infiltration of Metal Oxides into Sacrificial Polyester Fibers: Shape Replication and Controlled Porosity of Microporous/Mesoporous Oxide Monoliths". Chemistry of Materials. 23 (15): 3476–3485. doi:10.1021/cm200694w. ISSN 0897-4756.
  17. ^ Weisbord, Inbal; Shomrat, Neta; Azoulay, Rotem; Kaushansky, Alexander; Segal-Peretz, Tamar (2020-06-09). "Understanding and Controlling Polymer–Organometallic Precursor Interactions in Sequential Infiltration Synthesis". Chemistry of Materials. 32 (11): 4499–4508. doi:10.1021/acs.chemmater.0c00026. ISSN 0897-4756.
  18. ^ Parsons, Gregory N.; Atanasov, Sarah E.; Dandley, Erinn C.; Devine, Christina K.; Gong, Bo; Jur, Jesse S.; Lee, Kyoungmi; Oldham, Christopher J.; Peng, Qing; Spagnola, Joseph C.; Williams, Philip S. (December 2013). "Mechanisms and reactions during atomic layer deposition on polymers". Coordination Chemistry Reviews. 257 (23–24): 3323–3331. doi:10.1016/j.ccr.2013.07.001.
  19. ^ Leng, Collen Z.; Losego, Mark D. (2017). "Vapor phase infiltration (VPI) for transforming polymers into organic–inorganic hybrid materials: a critical review of current progress and future challenges". Materials Horizons. 4 (5): 747–771. doi:10.1039/C7MH00196G. ISSN 2051-6347.
  20. ^ Subramanian, Ashwanth; Tiwale, Nikhil; Nam, Chang-Yong (January 2019). "Review of Recent Advances in Applications of Vapor-Phase Material Infiltration Based on Atomic Layer Deposition". JOM. 71 (1): 185–196. Bibcode:2019JOM....71a.185S. doi:10.1007/s11837-018-3141-4. ISSN 1047-4838. OSTI 1491681. S2CID 255400603.
  21. ^ Azpitarte, Itxasne; Knez, Mato (September 2018). "Vapor phase infiltration: from a bioinspired process to technologic application, a prospective review". MRS Communications. 8 (3): 727–741. doi:10.1557/mrc.2018.126. ISSN 2159-6859. S2CID 104530697.
  22. ^ Subramanian, Ashwanth; Tiwale, Nikhil; Lee, Won-Il; Kisslinger, Kim; Lu, Ming; Stein, Aaron; Kim, Jiyoung; Nam, Chang-Yong (October 2023). "Vapor-Phase Infiltrated Organic–Inorganic Positive-Tone Hybrid Photoresist for Extreme UV Lithography". Advanced Materials Interfaces. 10 (28). doi:10.1002/admi.202300420. ISSN 2196-7350.
  23. ^ Barry, Edward; Libera, Joseph A.; Mane, Anil U.; Avila, Jason R.; DeVitis, David; Dyke, Keith Van; Elam, Jeffrey W.; Darling, Seth B. (2017-12-21). "Mitigating oil spills in the water column". Environmental Science: Water Research & Technology. 4 (1): 40–47. doi:10.1039/C7EW00265C. ISSN 2053-1419. OSTI 1402048.
  24. ^ Barry, Edward; Mane, Anil U.; Libera, Joseph A.; Elam, Jeffrey W.; Darling, Seth B. (2017-02-07). "Advanced oil sorbents using sequential infiltration synthesis". Journal of Materials Chemistry A. 5 (6): 2929–2935. doi:10.1039/C6TA09014A. ISSN 2050-7496.
  25. ^ Berman, Diana; Guha, Supratik; Lee, Byeongdu; Elam, Jeffrey W.; Darling, Seth B.; Shevchenko, Elena V. (2017-02-07). "Sequential Infiltration Synthesis for the Design of Low Refractive Index Surface Coatings with Controllable Thickness". ACS Nano. 11 (3): 2521–2530. doi:10.1021/acsnano.6b08361. ISSN 1936-0851. OSTI 1439858. PMID 28139905.
  26. ^ Chakrabarti, Bhaswar; Chan, Henry; Alam, Khan; Koneru, Aditya; Gage, Thomas E.; Ocola, Leonidas E.; Divan, Ralu; Rosenmann, Daniel; Khanna, Abhishek; Grisafe, Benjamin; Sanders, Toby; Datta, Suman; Arslan, Ilke; Sankaranarayan, Subramanian K. R. S.; Guha, Supratik (2021-03-01). "Nanoporous Dielectric Resistive Memories Using Sequential Infiltration Synthesis". ACS Nano. 15 (3): 4155–4164. doi:10.1021/acsnano.0c03201. ISSN 1936-0851. OSTI 1810325. PMID 33646747. S2CID 232089877.
  27. ^ Liapis, Andreas C.; Subramanian, Ashwanth; Cho, Sangyeon; Kisslinger, Kim; Nam, Chang-Yong; Yun, Seok-Hyun (2020-11-09). "Conformal Coating of Freestanding Particles by Vapor-Phase Infiltration". Advanced Materials Interfaces. 7 (24). doi:10.1002/admi.202001323. ISSN 2196-7350. PMC 7942784. PMID 33708471.
  28. ^ Ocola, Leonidas E.; Connolly, Aine; Gosztola, David J.; Schaller, Richard D.; Yanguas-Gil, Angel (2016-12-16). "Infiltrated Zinc Oxide in Poly(methyl methacrylate): An Atomic Cycle Growth Study". The Journal of Physical Chemistry C. 121 (3): 1893–1903. doi:10.1021/acs.jpcc.6b08007. ISSN 1932-7447.
  29. ^ Sweet, William J.; Oldham, Christopher J.; Parsons, Gregory N. (2014-11-06). "Conductivity and touch-sensor application for atomic layer deposition ZnO and Al:ZnO on nylon nonwoven fiber mats". Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films. 33 (1). doi:10.1116/1.4900718. ISSN 0734-2101.
  30. ^ Ocola, Leonidas E.; Wang, Yale; Divan, Ralu; Chen, Junhong (January 2019). "Multifunctional UV and Gas Sensors Based on Vertically Nanostructured Zinc Oxide: Volume Versus Surface Effect". Sensors. 19 (9): 2061. Bibcode:2019Senso..19.2061O. doi:10.3390/s19092061. ISSN 1424-8220. PMC 6539821. PMID 31052609.
  31. ^ Allen, Jonathan E.; Ray, Biswajit; Khan, M. Ryyan; Yager, Kevin G.; Alam, Muhammad A.; Black, Charles T. (2012-08-06). "Self-assembly of single dielectric nanoparticle layers and integration in polymer-based solar cells". Applied Physics Letters. 101 (6): 063105. Bibcode:2012ApPhL.101f3105A. doi:10.1063/1.4744928. ISSN 0003-6951.