Extended Klein Edges in Graphene Supporting Information
Extended Klein Edges in Graphene Kuang He,1 Alex. W. Robertson,1 Sungwoo Lee2, Euijoon Yoon,2 Gun-Do Lee,2 Jamie H. Warner1* 1
Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, United Kingdom.
2
Department of Materials Science and Engineering, Seoul National University, Seoul 151-742, Republic of Korea *[email protected]
Supporting Information
S1. Graphene nanoribbon fabrication process
Figure S1. Fabrication of graphene nanoribbons. (a – d) Schematic illustration of the fabrication process. (a) A focused electron beam has applied sequentially to two different regions on a pristine graphene sheet, two small holes are formed after 5 minutes and shown in (b). The electron beam is then spread to expose a larger area and allow edge atoms to be ejected. As a consequence, the size of the holes increase and the nanoribbon is formed between two holes as they narrow down to a thinner strip as shown in (d). (e) Experimental HRTEM image from the abovementioned process.
S2. Raw TEM images of extended Klein edges in a graphene nanoribbon
Figure S2. Raw TEM images of extended Klein edges in a graphene nanoribbon. (a-c) are the raw TEM images of Figure 1 (a, d, g) in the main text respectively. All scale bars are 1nm.
S3. Image processing
Figure S3. The various image processing techniques employed. (a) An unprocessed TEM image. (c) All the images in the main text have been initially subjected to a bandpass filter (ImageJ, filter large structures at 100px and small at 1px) to remove brightness variations.) The filter mask is shown in (b). (d) Gaussian blur with a sigma radius of 3.0 is applied to the image. (e) A false colour look up table (fire) is applied to the image and brightness and contrast adjusted to enhance visual contrast. (f-h) show the magnified images of the white box highlighted area in (a, c, d, e) respectively.
S4. Alignment of EK edges on two sides of GNR
Figure S4. EK edges on two side of the GNR. (a) The periodic EK edges on two sides of the nanoribbon show a symmetric behaviour. (b) The periodicity of EK edge on top row is offset by one atomic row compare to the bottom row.
S5. Density Functional Theory calculation of pristine and hydrogenated EK edges.
Figure S5. DFT calculation of pristine and hydrogenated EK edges. (a) and (b) are the front and side view of the pristine EK edge graphene ribbon, (c) and (d) are for hydrogenated EK edges. Blue rectangles indicate Klein edges region and red boxes indicate the within ribbon region.
Figure S6 White rectangle highlights the repeating units of the DFT calculation.
S6. Raw TEM images of extended Klein edges on the edge of bulk graphene
Figure S7. Raw TEM images of extended Klein edges on the edge of bulk graphene. (a-e) are the raw TEM images of Figure 4 (a, d, g, j, i) respectively. All scale bars are 1 nm.
S7. HRTEM images of EK edges at different holes without monochromator on
Figure S8. Non-monochromated TEM images containing EK edges. (a, c, e, f) are four TEM frames of one series, the EK edges are displayed in panels (b, d , e, f). Another EK edge was found in panel (g) and is shown in (h).
Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, United Kingdom.
2
Department of Materials Science and Engineering, Seoul National University, Seoul 151-742, Republic of Korea *[email protected]
Supporting Information
S1. Graphene nanoribbon fabrication process
Figure S1. Fabrication of graphene nanoribbons. (a – d) Schematic illustration of the fabrication process. (a) A focused electron beam has applied sequentially to two different regions on a pristine graphene sheet, two small holes are formed after 5 minutes and shown in (b). The electron beam is then spread to expose a larger area and allow edge atoms to be ejected. As a consequence, the size of the holes increase and the nanoribbon is formed between two holes as they narrow down to a thinner strip as shown in (d). (e) Experimental HRTEM image from the abovementioned process.
S2. Raw TEM images of extended Klein edges in a graphene nanoribbon
Figure S2. Raw TEM images of extended Klein edges in a graphene nanoribbon. (a-c) are the raw TEM images of Figure 1 (a, d, g) in the main text respectively. All scale bars are 1nm.
S3. Image processing
Figure S3. The various image processing techniques employed. (a) An unprocessed TEM image. (c) All the images in the main text have been initially subjected to a bandpass filter (ImageJ, filter large structures at 100px and small at 1px) to remove brightness variations.) The filter mask is shown in (b). (d) Gaussian blur with a sigma radius of 3.0 is applied to the image. (e) A false colour look up table (fire) is applied to the image and brightness and contrast adjusted to enhance visual contrast. (f-h) show the magnified images of the white box highlighted area in (a, c, d, e) respectively.
S4. Alignment of EK edges on two sides of GNR
Figure S4. EK edges on two side of the GNR. (a) The periodic EK edges on two sides of the nanoribbon show a symmetric behaviour. (b) The periodicity of EK edge on top row is offset by one atomic row compare to the bottom row.
S5. Density Functional Theory calculation of pristine and hydrogenated EK edges.
Figure S5. DFT calculation of pristine and hydrogenated EK edges. (a) and (b) are the front and side view of the pristine EK edge graphene ribbon, (c) and (d) are for hydrogenated EK edges. Blue rectangles indicate Klein edges region and red boxes indicate the within ribbon region.
Figure S6 White rectangle highlights the repeating units of the DFT calculation.
S6. Raw TEM images of extended Klein edges on the edge of bulk graphene
Figure S7. Raw TEM images of extended Klein edges on the edge of bulk graphene. (a-e) are the raw TEM images of Figure 4 (a, d, g, j, i) respectively. All scale bars are 1 nm.
S7. HRTEM images of EK edges at different holes without monochromator on
Figure S8. Non-monochromated TEM images containing EK edges. (a, c, e, f) are four TEM frames of one series, the EK edges are displayed in panels (b, d , e, f). Another EK edge was found in panel (g) and is shown in (h).
