Interview: Steven Blankenship
2013 George Hanyo Award Recipient
Interviewed by Paul Holloway, October 29, 2013
HOLLOWAY: Good afternoon. My name is Paul Holloway. I’m a member of the AVS History Committee. Today is Tuesday, October 29, 2013, and we’re at the 60th annual International Symposium of the AVS in Long Beach, California. Today I have the pleasure of interviewing Steven R. Blankenship from NIST, who is the Hanyo Award winner for 2013. His citation reads: “For outstanding contributions to the scanning tunneling microscopy user facility and other laboratories at the Center for Nanoscale Science and Technology at the National Institution of Standards and Technology.” So congratulations on the award, Steven.
BLANKENSHIP: Thank you.
HOLLOWAY: Could you begin by giving us a date and place of birth?
BLANKENSHIP: October 4, 1972 in Lynchburg, Virginia.
HOLLOWAY: Very good. How about your educational background?
BLANKENSHIP: Background was Mary Washington College (now Mary Washington University). I did a Bachelor’s of Science degree in Physics. Beyond that, I went to VCU for a master’s degree in physics.
HOLLOWAY: VCU is Virginia Commonwealth University?
BLANKENSHIP: Virginia Commonwealth University. Yes, sir.
HOLLOWAY: Okay. M.S.in physics?
BLANKENSHIP: Yes, sir.
HOLLOWAY: Okay. And Mary Washington College is where?
BLANKENSHIP: Fredericksburg, Virginia.
HOLLOWAY: So Mary Washington was the bachelor’s degree.
BLANKENSHIP: Yes, sir.
HOLLOWAY: And VCU was a Master’s degree.
BLANKENSHIP: And VCU was the master’s.
HOLLOWAY: Good. Both in physics.
BLANKENSHIP: Yes, sir.
HOLLOWAY: Okay. Tell us a little bit about how you got into the sciences and why you chose physics.
BLANKENSHIP: Well, I was always interested in how things worked and I enjoyed mathematics. I wanted to be an engineering major in the beginning, and some things worked out to where I got interested in physics. At Mary Washington, the physics courses fit my schedule and I really liked what I was learning, so I stuck with it. Then after graduation, I decided to pursue physics down at Virginia Commonwealth.
HOLLOWAY: So did you go directly from Mary Washington to VCU with no break, no work experience?
BLANKENSHIP: Yes, sir.
HOLLOWAY: Okay. What did you do after VCU?
BLANKENSHIP: After VCU, I started directly at NIST.
HOLLOWAY: What year was that?
BLANKENSHIP: That was 1999.
HOLLOWAY: 1999. You just barely got in there before 2000 came around. Where did you start there? Where was your first job?
BLANKENSHIP: The first job there was within the Electron Physics Group working with Joe Stroscio and Bob Celotta on bringing up the new low temperature STM facility.
HOLLOWAY: Well, that was quite a challenge, I’m sure.
BLANKENSHIP: A very big challenge. You’d walk into the room and there are just these huge chambers everywhere and it’s all integrated system. So it was a big change from what I was used to.
HOLLOWAY: So had you worked with vacuum before you worked with these systems?
BLANKENSHIP: Yes, sir. At VCU, I worked with John Carlisle, and he taught me a lot about, vacuum systems, vacuum systems designs and various surface science techniques.
HOLLOWAY: Carlisle was a physics professor?
BLANKENSHIP: Yes sir, at VCU.
HOLLOWAY: And what did he do for research?
BLANKENSHIP: He was doing surface science back then.
HOLLOWAY: So Auger electron or XPS or AFM?
BLANKENSHIP: We were doing Auger, STM, RHEED.
HOLLOWAY: A little bit of everything.
BLANKENSHIP: A little bit of everything, yeah.
HOLLOWAY: What did you do for your master’s? A specific project?
BLANKENSHIP: For my master’s, I characterized silver on silicon (5 5 12).
HOLLOWAY: Oh, is that right?
BLANKENSHIP: Yes, sir.
HOLLOWAY: Do you remember the details of what you found with that?
BLANKENSHIP: I don't remember all the details, but I know we went through the phase diagram for the silicon (5 5 12) surface growing the silver on it. We characterized it, and then we would go to like the ALS or the Synchrotron Radiation Center and we would do spectroscopy on those. We were just trying to characterize what was going on.
HOLLOWAY: So which spectrometer did you go to? Did you go to Brookhaven?
BLANKENSHIP: No. It was Advanced Light Source (ALS).
HOLLOWAY: Out in California.
BLANKENSHIP: In Berkeley, yes sir, and the Synchrotron Radiation Center in Wisconsin.
HOLLOWAY: I see. So did you get to go to Wisconsin in the wintertime?
BLANKENSHIP: Yes sir, I did, and it was cold.
HOLLOWAY: So you got second prize then, huh? [Laughter]
BLANKENSHIP: Yeah!
HOLLOWAY: They would send you out there in the wintertime, and then they would go to California in the wintertime, I suspect.
BLANKENSHIP: Yes, yes.
HOLLOWAY: Tell me a little bit about the Electron Physics Group. You said you worked with Stroscio and…
BLANKENSHIP: And Bob Celotta.
HOLLOWAY: Celotta.
BLANKENSHIP: And John Unguris, Dan Pierce, and Jabez McClelland. I mean I worked with all of those guys.
HOLLOWAY: What were they studying at that time?
BLANKENSHIP: At that time, Stroscio was building up the new Low Temperature STM system. John Unguris who has doing SEMPA, Scanning Electron Microscopy with Polarization Analysis. Jabez McClelland was doing some laser trapping. Dan Pierce was doing room temperature STM experiments. I was kind of like the utility guy. I came in and I helped everybody do different things.
HOLLOWAY: You made sure that they made some progress. I don't remember the year that Binnig and Rohrer got the Nobel Prize for the STM. Do you?
BLANKENSHIP: I do not recall the actual year.
HOLLOWAY: So the design of the systems that you were putting together, did you make that design yourself or did they adapt it off of other people?
BLANKENSHIP: That was Joe’s design. He focused on that, and I helped him assemble the STM. But as far as all the vacuum components, pumps, and putting things together, I was the one in charge of doing that.
HOLLOWAY: You were the big sucker in the whole process.
BLANKENSHIP: Yeah. I was a stainless steel maniac at that time.
HOLLOWAY: Is that right?
BLANKENSHIP: Yes.
HOLLOWAY: So you worked with them until what year? Or are you still working with them?
BLANKENSHIP: Still working with them.
HOLLOWAY: With that group.
BLANKENSHIP: Yeah, although we’ve changed. We’re now the Center for Nanoscale Science and Technology, and we’ve expanded. But I’m still within the Electron Physics Group.
HOLLOWAY: So are you officially associated with the center then?
BLANKENSHIP: Yes, sir.
HOLLOWAY: Your services are dedicated to the center and not available to the balance of NIST, except under extraordinary conditions?
BLANKENSHIP: We do work sometimes outside if somebody needs help. You know, we’ve had people come to us with older ion pumps and they couldn’t figure out what was wrong. So we would go over, myself and our electronics engineer, and help them diagnose, take it apart, and fix it for them. But most of the time we’re within the CNST and helping out all the scientists get their experiments up and running. Or if they need something, we’ll design it for them in a CAD program, see it through to the finished product, and install it for them and help them get it running.
HOLLOWAY: So most of the vacuum systems you work with are all dry vacuum or there’s…
BLANKENSHIP: The majority of them are. We do have some oil backed systems that are just high vacuum. So I’m always trying to use conflat-flanges and things like that to get to UHV, but with the high vacuum systems we can utilize orings and KF flanges for sealing purposes.
HOLLOWAY: And save a little bit on the cost.
BLANKENSHIP: Save a little bit on the cost, yes.
HOLLOWAY: Do you use mainly ion pumps or a variety of pumps?
BLANKENSHIP: Different systems like our new ultra-high vacuum STM, or ultra-low temperature STM facility, we use cryopumps, ion pumps, ion pumps with TSPs, turbo pumps. We’ll back the turbo pumps with either scroll pumps or sometimes diaphragm pumps. It just depends on what size pump we’re using and what chamber volume is.
HOLLOWAY: So you said UHV, ultra-high vacuum?
BLANKENSHIP: It’s ultra-high vacuum.
HOLLOWAY: So 10-10, 10-11?
BLANKENSHIP: We’re in the low 11s, yes sir.
HOLLOWAY: Low 11s. So you do a lot of baking out of your systems then.
BLANKENSHIP: Oh yeah.
HOLLOWAY: That’s why you’re a stainless steel man.
BLANKENSHIP: Yes. Yes.
HOLLOWAY: What type of gauging do you use for that?
BLANKENSHIP: Cold cathode gauges. The majority of it is cold cathode.
HOLLOWAY: It’s either cold cathode or able to start and measure 10-11?
BLANKENSHIP: They will get down to 10-11 and sometimes it will flake out a little bit and go under range like it can’t read, but then it will kick back on. So I think it’s getting to the limitation of those gauges.
HOLLOWAY: You have a starter filament to…
BLANKENSHIP: Not on those, no.
HOLLOWAY: Not on those? But you don’t use any of the Redhead gauges…
BLANKENSHIP: No, I haven’t used any of those.
HOLLOWAY: …or any of those cyclotron gauges?
BLANKENSHIP: No. I’ve been to a couple of those XHV conferences where Redhead actually gave talks on those, and I was interested in them. But we haven’t gone there yet.
HOLLOWAY: Okay. You do computer-aided design of your systems before you actually start your assembly then?
BLANKENSHIP: Yes, sir. Most of our stuff—actually all of our stuff in the majority of labs is all custom. So we will design everything from the bottom up on the CAD system, and then we’ll get everything made from there.
HOLLOWAY: So what was your biggest challenge in the scanning tunneling microscope systems?
BLANKENSHIP: Probably the newer facility is separated into two different rooms. So we have a large area room where the STM is located, and it’s shut off to decouple any vibrations or noise from the sample and tip preparation room. Just trying to figure out how to couple these two together to get samples and tips transferred through UHV was a big challenge. We finally came up with a way to do it. We’ve made a portable vacuum system that we could just roll in and out and decouple and couple as we needed.
HOLLOWAY: Is that right?
BLANKENSHIP: Actually did some work with McAllister to make some custom components where we would only have to bakeout the little coupling regions, which made it a lot easier than having to bakeout the entire 8-foot section that joined the two labs together.
HOLLOWAY: So what sort of a joining technique do you use to go from your XPS system to the transfer to the AFM system, STM system?
BLANKENSHIP: It is all conflat systems, 10-inch conflats. We have 10-inch conflats on each end as a stop, and then the portable system has 10-inch gate valves. We have some custom bellows systems that we can slide the system into place and then uncollapse the bellows until they join and then connect them that way.
HOLLOWAY: So if you want to transfer a sample, you hook up this to your source system, you bake out the volume between the two gate valves. How do you do your bake then? Do you do a bake?
BLANKENSHIP: The bake is done at each end of the portable system, there are two bellows. One couples to the STM chamber; one couples back to the MBE tip preparation room.
HOLLOWAY: I see.
BLANKENSHIP: And we only bake those two little sections. It’s about a 12-inch section by the 10-inch bellows diameter. . We utilize gatevalves with pump out ports on them. So we can pump the bellows volumes directly thru the ports and bake the two individual sections at each end of the 8-foot length of the portable section.
HOLLOWAY: So how low can you get that in pressure?
BLANKENSHIP: We normally will hook that up, pump it, bake it for a minimum 24-hour period, and then open back up to the main systems. The pressures will fall to low 10s or high 11s. So then we’ll go and grab our samples and tips and transfer them through all the way to the STM side.
HOLLOWAY: Are your gate valves metal-sealed gate valves?
BLANKENSHIP: Yes, sir.
HOLLOWAY: Okay. So you can bake them.
BLANKENSHIP: Yes.
HOLLOWAY: Even closed?
BLANKENSHIP: Yes. We don’t have a problem with them.
HOLLOWAY: Good. Let’s come back to the people you work with. You mentioned a couple. Are there others that you would like to mention as being mentors for you or being colleagues that you work with?
BLANKENSHIP: Well, I think I mentioned John Carlisle which was my advisor for my master’s. I owe a lot to him because he trained me and got me started from the beginning. I learned an awful lot from him, and I’m grateful for all that he taught me.
HOLLOWAY: Is he still active at VCU?
BLANKENSHIP: No, he’s not at VCU now. The last I heard, he was at, I believe, Argonne, but he may have left there and gone on to do some diamond thin film coatings. I haven’t been in touch with him in a while.
HOLLOWAY: What about Mary Washington College? Did you do any research there?
BLANKENSHIP: I didn’t do any research there. It was a really small college, so there was no research done there. I was a baseball player, so half of my time was on the field; half of my time was in the classroom.
HOLLOWAY: So you’ve been watching the World Series?
BLANKENSHIP: Oh yes, sir.
HOLLOWAY: Who are you rooting for?
BLANKENSHIP: Well, I’m a Yankees fan, but I have to root for the American League. So I’m rooting for Boston, but being a Yankees fan, you can’t really say that.
HOLLOWAY: You can’t say that.
BLANKENSHIP: No.
HOLLOWAY: We’ll have to edit that out. [Laughter]
BLANKENSHIP: Yeah.
HOLLOWAY: What did you think of that interference call?
BLANKENSHIP: I called it right away. It was a good call, but you hate to see a game end that way.
HOLLOWAY: Yeah, that’s right.
BLANKENSHIP: You know, that’s just the way it goes sometimes.
HOLLOWAY: Who do you think is going to win?
BLANKENSHIP: I think Boston may win it. It may be in seven games, though. I think the Cardinals are going to come back strong here in this next game.
HOLLOWAY: Yeah. I think they’re motivated. It’s a good series.
BLANKENSHIP: It is. It’s a great series, yes.
HOLLOWAY: So what position did you play?
BLANKENSHIP: I was a shortstop in college, and I loved it. I miss it.
HOLLOWAY: So you didn’t play on the VCU team?
BLANKENSHIP: I didn’t play on the VCU team. I played on the Mary Washington team. It was a good time. I really enjoyed it.
HOLLOWAY: Those are very competitive. College teams are very competitive nowadays.
BLANKENSHIP: Yes. Very competitive.
HOLLOWAY: We have a reasonable coach and a reasonable team at Florida.
BLANKENSHIP: Yeah. You all have better weather down there, so you can get outside earlier and practice longer.
HOLLOWAY: Yeah. We get outside and everybody wants to come down and play practice games with us. So there’s quite a practice schedule down there.
BLANKENSHIP: I remember those days.
HOLLOWAY: Tell me about achieving low temperature in your vacuum systems and in your STM system.
BLANKENSHIP: So we built a…Well, we didn’t build it. We worked with Janis Research Company with one of their dilution refrigerators. It was a fun project. We did a lot of testing of materials to make sure they were UHV compatible. Also some thermometry testing so we could actually measure the temperatures. So right now I think the paper that was put out was advertising it’s a 10 milliKelvin STM, and I believe we’ve actually done better than that.
HOLLOWAY: To get 10 milliKelvin, do you have to pump? So you isolate it with a vacuum.
BLANKENSHIP: Yes.
HOLLOWAY: And you just use a dilution refrigerator for the cooling, and you put head feedthroughs into the vacuum system for the head and you get the dilution cooling process.
BLANKENSHIP: Yeah. So there’s actually a gas handling system that we can recirculate the helium-3 through the system to help cool it down further.
HOLLOWAY: So do you purify it to helium-3 or do you have—
BLANKENSHIP: It is already purified, and it’s in its own…It’s a separate loop in the system to do that.
HOLLOWAY: I see. How frequently do you have a leak on that sucker, the dilution refrigerator?
BLANKENSHIP: You know what? I’m trying to think. I don't think—If we have, we’ve only had one. It’s a pretty robust system, and we haven’t had any issues with it luckily.
HOLLOWAY: So how carefully do you have to pay attention to the thermal conductivity and heat sinks that you attach to the…How do you isolate the sample from the walls which are not going to be at 10 milliKelvin?
BLANKENSHIP: Very carefully. So all the wires that lead down to the feed through for the STM come all the way down the dilution refrigerator. So there are heat anchors all the way down. In different stages they get heat sunk to the very bottom. There are radiation shields that we can drop in from the top to block any radiation from coming from the top.
HOLLOWAY: So you have the vacuum vessel walls that are room temperature.
BLANKENSHIP: They are not at room temperature because they’re down in the helium dewar. So they’re cooled that way.
HOLLOWAY: I see. So those walls are what sort of a temperature then?
BLANKENSHIP: I would say they’re around 4 Kelvin or so.
HOLLOWAY: You must have some arrangement for minimizing icing and those condensation problems.
BLANKENSHIP: Well, the insert, which the UHV is directly inside of it. There’s no exchange gas region in this system. It’s dropped directly into the helium.
HOLLOWAY: Oh. So it’s in a helium bath.
BLANKENSHIP: It’s in a helium bath.
HOLLOWAY: I see.
BLANKENSHIP: When we do have to work on it or pull it out, you will get the icing on it when it comes up out of the dewar. But as far as any ice or condensation directly in the bath, we don’t really see any issues with that.
HOLLOWAY: So you capture all your helium gas release and recondense it back down again?
BLANKENSHIP: We don’t, but we’re getting ready to look into doing that. So we will fill the dewar with helium and then the boil off from that blows off into the atmosphere. But we’re going to start recapturing that. We’re looking into doing that now.
HOLLOWAY: I would think that would be motivated by cost.
BLANKENSHIP: By cost, yeah. Especially with the price of helium the way it is right now.
HOLLOWAY: So in some cases they stage these things between room temperature to liquid nitrogen to liquid helium to lower.
BLANKENSHIP: Right.
HOLLOWAY: Is that sort of the design? But you don’t have to do that. Well, you would to maintain your reservoir of liquid helium, I presume.
BLANKENSHIP: Right. Right. Yes.
HOLLOWAY: So you have liquid nitrogen shroud around this helium bath?
BLANKENSHIP: On the new system, we do not have the liquid nitrogen shroud around it. It’s a vacuum dewar.
HOLLOWAY: I see. Just the vacuum isolation.
BLANKENSHIP: Yes. So when you start out, you start with liquid nitrogen to pre-cool everything down, and then you pump and flush that out of the system and then you’ll fill with helium. Our whole time…We fill with helium maybe once every 11 days.
HOLLOWAY: That’s a pretty good record. So tell me about…You’re responsible for an experimental design, construction, and system maintenance and troubleshooting.
BLANKENSHIP: Oh yeah.
HOLLOWAY: You do it all.
BLANKENSHIP: Yeah, we do it all. A lot of pumps, a lot of pump problems. We try to take them apart and diagnose what’s wrong with them and get them fixed and back online as soon as possible.
HOLLOWAY: So you have a lot of these closed-loop helium refrigeration cryopumps?
BLANKENSHIP: We have one of those, one of the closed-loop dilution refrigerators. But like vacuum pumps and stuff like that, for the research side of CNST, a lot of pump issues come up. Gauges, you know, you have to take them apart and clean them every now and then for them to work, so I’m in charge of doing that.
HOLLOWAY: How does the Center for Nanoscale Science and Technology interact with the standards and techniques objectives of NIST? That’s a loaded question.
BLANKENSHIP: That’s a loaded question. [Laughter] That is a loaded question. I’m not real sure how to answer that one. Hmm.
HOLLOWAY: So in the Center, do they characterize many of the nanoparticle samples using the AFM, STM or…
BLANKENSHIP: Yes.
HOLLOWAY: Now in terms of nanoparticle synthesis, you can do a bottoms-up or a tops-down approach, where I mean by tops-down you take a thin film, put it on a substrate, and then you either pattern it with lithography and/or you agglomerate it with heating it a little bit to get atomic processes to make islands versus colloidal where you grow it out of a solution. It may be a hot solution. Then purify it and put it in the vacuum system. Do you…
BLANKENSHIP: I think they do a little bit of both. A lot of the guys will go and synthesize their samples in the clean room using the CNST facilities. Then they will bring those samples back and we’ll insert them into the STM. We also have the MBE chambers where we’ll take a blank sample and grow what we want to grow on it, and then we can characterize it that way.
HOLLOWAY: Do you live in the Washington area?
BLANKENSHIP: I live outside of Washington in northern Virginia, a rural part of Virginia.
HOLLOWAY: It must be nicer up there.
BLANKENSHIP: Yes.
HOLLOWAY: It’s good to be there on the weekends, I’m sure.
BLANKENSHIP: Oh yeah.
HOLLOWAY: What advice would you have for young people in terms of trying to achieve recognition with the company they work with so that they could achieve the Hanyo Award, for example?
BLANKENSHIP: I would just have to say give 100% and do as much as you can to help as many people as you can. I wasn’t really looking for recognition. I was surprised when somebody told me. They were like, “Yeah, you got this.” I’m like, “Well, I had no idea.” You know, the guys that I work with are great, and the whole group is great to work for a bunch of great guys and girls. We all work together well, and that’s a key part of it, that you like the people you work with and you enjoy interacting with them. They also give you the freedom to go and try something new. When you do something like that (you have that freedom), it pays off in the end sometimes. Sometimes it doesn't, but you learn from your mistakes and then you keep going. You just never quit.
HOLLOWAY: Tell me about how you learn about new opportunities, new technologies. Do you learn that by reading, by going through magazines, by going to AVS meetings, for example?
BLANKENSHIP: Yeah. It’s a combination of all of that. Going to meetings, reading, the magazines that you get sent. Also, the post-docs that we have coming in. We have a turnover of post-docs every two years. Sometimes they’ve been doing something new in a different part of the world, and we haven’t heard about it yet. You get that information through exchange with them. So it’s a combination of all of that.
HOLLOWAY: So meeting people and networking.
BLANKENSHIP: Networking, yes.
HOLLOWAY For lack of a better word. It’s a well-worn phrase, but that’s important.
BLANKENSHIP: Yes, sir. Very important.
HOLLOWAY: Good. Well, I think that covers about what I wanted to cover in the interview. Have you got anything you’d like to add?
BLANKENSHIP: No, sir. That’s pretty good. I’m fine.
HOLLOWAY: Okay. Well, congratulations again, Steven, on earning the Hanyo Award for 2013.
BLANKENSHIP: All right. Thank you very much.