Entries

Thu, November 29, 2007

Sulfite and Sulfate on Ag(111) Surface [Research]

Stabilization of Surface Reaction Intermediates by Added Metal
Atoms on Metal Surfaces of Low Free Energy

Ling Zhou, Weiwei Gao, Andreas Klust, and Robert J. Madix
Journal of Chemical Physics

Weiwei posted @ 13:17:24 || Cambridge, MA ||

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Sun, August 26, 2007

ACS Meeting in Boston [Research]

It was ACS meeting this past week in Boston. I had an oral presentation and poster presentation. They all went pretty well. I felt what you could learn from this kind of huge national meeting was actually very limited because the subjects were so diverse.

It was a good experience to meet with Professor Haruta. (Professor Haruta was the first person to find gold catalysis.) We had lunch together. Dilini and I also showed him the lab and the campus.

Weiwei posted @ 19:41:58 || Cambridge, MA ||

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Tue, June 26, 2007

Essay - Growth (from Nature) [Research]

For some reason I was touched by this small essay. I guess I believe 'post-doc' is the most 'unattactive' stage in an academic path. But from my experience, I also feel it's the stage where I absorbed most knowledge. Keep faith - we supposed to shine not to fade!

Weiwei posted @ 09:15:42 || Cambridge, MA ||

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Mon, May 21, 2007

Essay - Question Araised (from Nature) [Research]

Weiwei posted @ 12:48:57 || Cambridge, MA ||

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Sun, May 06, 2007

Interaction Between Chlorine and Au-O Complexes [Research]

Interaction Between Chlorine and Au-O Complexes

Weiwei Gao, Ling Zhou, Dilini S. Pinnaduwage, Cynthia M. Friend
Journal of Physical Chemistry C

Weiwei posted @ 18:48:06 || Cambridge, MA ||

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Mon, November 13, 2006

Chlorine Promotion Effect on Au Surface [Research]

Chlorine Promotion of Styrene Epoxidation on Au(111):
A Low-temperature and High-selective Catalytic Process

Dilini S. Pinnaduwage(a), Ling Zhou(a), Weiwei Gao(b), Cynthia M. Friend(a)(b)*
Journal of American Chemical Society

Weiwei posted @ 14:50:03 || Cambridge, MA ||

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Fri, February 10, 2006

Some Updates [Research]

Not too much happened in the week. I was basically busy in the lab as usual. I am happy with the progress of the experiments. The above are two STM images I just got showing the titanium oxide clusters on gold surface. There is still a lot too do but so far it's interesting.

It gets really cold recently, which is supposed to be normal in New England. But people are getting more passive with the temperature's getting colder. Especially there is a big storm coming tomorrow. So stay warm and safe!

Weiwei posted @ 14:33:32 || Cambridge, MA ||

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Sat, January 14, 2006

Science Week Topics [Research]

I will post some information from Science Week if it's related to the catalysis, surface sciences or material sciences.

Lateral Hopping Requires Molecular Rocking
Science 310(2005)1774 [pdf]
Related information from Science Week [link]

Weiwei posted @ 11:57:19 || Cambridge, MA ||

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Sat, December 10, 2005

Imaging Gold (111) Surface - Update [Research]

After several more days of stressful work, I finally had the image of the herringbone structure on gold (111) surface. Dilini and I worked most day of today and finally got the images. The research work most of the time is so frustrating that you would never think anything good would happen. But even the smallest results will pay off all the hard work.

Weiwei posted @ 17:08:35 || Cambridge, MA ||

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Mon, December 05, 2005

Imaging Gold (111) Surface [Research]

Dilini and I obtained good STM images of Au (111) surface today. The STM image on the left shows clear steps on the surface. The reconstruction of this surface can be seen in the big terrace but it's not very good.

Gold is a surface easy to image. It's not a big deal to get STM image of this surface. But the point is the STM system goes back to work. The very hard work of the past month is paid off. From the past month's work, I learned a lot and got familiar with the system. There are still more difficulties ahead and there still a lot to do but I think this is a good start.

Weiwei posted @ 17:04:40 || Cambridge, MA ||

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Sun, November 27, 2005

New STM System [Research]

I have been working on the new STM system for a couple of weeks since I came to Harvard. I am trying all my best very hard but still don't know when I can get some good results.

I started with the bad ion pump followed by all sorts of problems. The chamber was leaking. The gate valve did not work. The solder was degassing badly. The wire connection on STM was wrong......The problems of the instrument are actually very normal for surface science research but the difference between now and the time when I was at Yale is that there would be no one to help.

The problem was solved one by one anyway. It's tough but I hope I am approaching the good end.

Weiwei posted @ 15:35:44 || Cambridge, MA ||

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Mon, October 17, 2005

Inside of An Effusion Cell [Research]

Hui continuouly had problem with her effusion cell and eventually we had a chance to peel everything off and take a look at the inside. This is really a good chance because the cell costs a lot and we usually handle it very carefully.

When we looked inside, we realized that there's nothing fancy. The thick tungsten wire is used to heat the crucible and the every thin wires are used to support the heating wire. The ceramic tubes are used to support everything and make sure there is no short. So the reason why it's wrapped that complicated is they don't want to you find out what's inside.

Weiwei posted @ 15:53:48 || New Haven, CT ||

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Thu, August 11, 2005

Job Settled Down [Research]

It took me about half a year to finally settle down my job. I am going to work at Harvard with Professor Friend as a post-doctor in November 1st in Chemistry Department.

> I need to thank Dr. Chambers in Pacific Northwest National Lab, who also offered me a position. Both positions are equally good and it's a hard decision for me to decline the offer.

> I also need to thank Prof. Altman (my advisor), Prof. Henrich and Prof. Walz, who wrote the recommendation letters for me. Without their recommendations and help, I would not be able to move to the next step.

> I also need to thank my parents and my good friends: Hong Xia, Zhang Liangfang, Li Min, Wang Jun, Huiqiong, Andy, and David (in case I forget any names here I am extremely sorry). Without their encouragement, I would not go thru this painful process.

Well I learned that job searching is a big task. Patience is the most important thing!

Weiwei posted @ 21:56:20 || New Haven, CT ||

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Sat, July 30, 2005

Visit Pacific Northwest National Lab [Research]

I had a very nice visit to Dr. Scott Chambers in Pacific Northwest National Lab in Richland, WA. This is the first time I have been to the west. It took about 7 hours to fly there. It's basically a trip across the nation.

I can immediately feel the difference of the two places. (I mean New Haven and the Richland.) Not only the desert scene, not only the very dry weather but the people look different. However I just can not say exactly what's the difference. It's just the different feeling.

The national lab also has a lot of differences with the university. People here are more like working on a job. They look very professional - the whole thing they do is experiment. However in the university you can see different people - both students and professors and people from different background.

This is also a very intellectual stimulating visit. I met several scientists whom I have admired for a long time. Moreover during the flying, I saw the Great Salt Lake. I have known the lake since I was just a kid. Now I eventually saw it.

Weiwei posted @ 19:45:41 || New Haven, CT ||

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Fri, June 24, 2005

Imagin Anatase (001) Surface [Research]

I stayed up all last night in the lab, imaging the anatase (001) surface. It's cool I got atomic resolution. You can see the image on the right. The rows show the (1x4) reconstruction on the surface. I have been working on this for several weeks and finally got this little bit progress.

However with the image I also found some problem of the STM. The atomic rows on the adjacent steps are supposed to be perpendicular but they are not on the image. Well something is wrong with the hardware and we need to figure it out.

Recently all the people squizzed into the same system, which makes the experiment time very limited for each of us. So I need to work on some wired time schedule. And also I need to work on my thesis.

Weiwei posted @ 19:28:18 || New Haven, CT ||

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Fri, May 13, 2005

Student Travel Fund and Some Updates [Research]

I got the graduate student travel fund for the meeting next week to Mass from the Graduate Student Associate. I am pretty glad with it. I will give a presentation. Professor I. E. Wachs will be there, who has done so much pioneeirng work in the supported oxides catalysis.

I am very busy this week with the STM experiment. We have solved two big problems that have hindered our research a lot: one is the heater and the other is to make the anatase film conductive enough so that we can do STM experiment. Seems like the rest of the work is to do the real imaging, which is not easy at all.

Below is a picture I saw on a website. It's the scene of south China (Gui Lin) and it's amazingly beautiful. I really like it.

Weiwei posted @ 14:05:34 || New Haven, CT ||

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Tue, May 03, 2005

Growing Anatase TiO2 (001) [Research]

Even though growing anatase TiO2 (001) is my first PhD experiment project, I am still happy for my these two days' work of growing another film. The most important reason is that we solved the problem of the heating in O2 enviroment, which has retarded my progress for a very long time.

The reliable heating will make my next several projects much easier. Seems like I am again powered up for my research work - the feeling I miss so much.

Weiwei posted @ 18:42:09 || New Haven, CT ||

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Sat, April 30, 2005

UHV / O2 Heating [Research]

Heating in high O2 pressure enviroment has been a big issue for me ever since we set up the chamber. The heater filament tends to be oxidized during the heating, which makes the heat very short life time. The commercial heater we were using, even though claiming heating in O2, still does not have very long lasting time. And it really cost a lot.

After we burnt several heaters, I broke one in part and tried to figure out how it was made. The fact is it's actually not complicate at all. So I made one with relatively cheap material. From its test performance, it works very well. I am happy with the results.

I spent several hours today to put the heater into the chamber. For several months, my experiment has been retarded by the problem of the heater. I hope now it will be solved. And I am pretty optimistic with that.

Weiwei posted @ 14:29:48 || New Haven, CT ||

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Tue, April 26, 2005

Paper to Thin Solid Film [Research]

We got the paper to Thin Solid Film in press today. This one is solely focused on the thin film growth, which is the subject I like most. [full text in pdf]

Weiwei posted @ 09:02:16 || New Haven, CT ||

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Thu, February 24, 2005

LaAlO3 (101) Surface [Research]

Now I started my final bit of research project. It is more related to the anatase TiO2 and the using of STM. I think it's not a big task and I should have plenty of time to do it.

The image on the right-hand side is the LEED pattern of the annealed LaAlO3 (101) surface. It shows a very clear 1x3 reconstruction. This is some supplement research. But since few people has studied this surface, we might be able to get something interesting.

Weiwei posted @ 14:46:49 || New Haven, CT ||

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Tue, February 08, 2005

STM Tip Reflection and Approaching [Research]

We had very difficult time before when doing STM experiments. The problem was that we could not find the very clear reflection of the STM tip to do the tip approaching.* Several months ago, Min and I spent four days trying to solve the problem. Four days seemed very long. We constantly found parts that need to be modified. But eventually it works very well. Now we saved a lot of time to finish this work.

Tip approaching is only a very small part of the experiment. But anyway, we have made the progress.

*ps: When STM is working, the tip is so close to the sample surface that the tunneling current can go from tip to sample or reverse. To do so we need to set the tip to a very close position to the sample surface. This is the tip approaching.

Weiwei posted @ 18:48:39 || New Haven, CT ||

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Fri, February 04, 2005

Paper to Thin Solid Films [Research]

I just heard that my paper of "Growth of anatase films on vicinal and flat LaAlO3 (110) substrates by oixygen plasma-assisted molecular beam epitaxy" has been accepted by Thin Solid Films and will be published soon. Although the minor revisions are needed, there should be no problem.

Weiwei posted @ 12:17:15 || New Haven, CT ||

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Tue, February 01, 2005

Growing WO3 Film [Research]

This is the first time I worked so intensively in the lab since I came back. Min and I grew a new tungstern film. We met several problems during the process and nearly gave up. However, we solved all of them and the film turned out pretty good. The problems of the heater and the substrate are also solved, which is very good.

Weiwei posted @ 13:14:20 || New Haven, CT ||

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Fri, December 03, 2004

The 2nd Robert Langer Graduate Symposium [Research]

Today is the 2nd Chemical Engineering Robert Langer Graduate Student Symposium. It seems that the whole event is great success - everything goes smoothly as we have expected. And the good point is that the department now has the funding for every year. So the symposium will be a yearly event!

I am glad that I am in the committee and did some work for the symposium. The fun part is chairing the afternoon session. This is the first time I do the chairing. You have to watch the time and remind the speaker when the time is running out. Plus you have to listen to the talk very carefully. In case nobody ask the question, you have to ask the speaker. But everything goes well and I am glad with it.

We had a very good banquet last night at the Quinippiac Club. Seems that everyone enjoyed the food!

Weiwei posted @ 21:30:37 || New Haven, CT ||

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Tue, October 26, 2004

Imaging Graphite Surface [Research]

We finally made some progress in tuning always-has-trouble STM. We got atomic resolution images of the graphite. It's supposed to be easy to image graphite sample - you even do not need to clean the sample. The images we got are not very high quality but it's quite enough to calibrate the STM.

I made a mistake last night to turn off the cooling water of the X-ray source even did not take a look at that Jun was running the experiment. Well bad things happened. The magnesium window of the x-ray source blowed out and the anode was melt. I am extemely sorry for what had happened.

The pain on my neck was getting worse today...well I need to go to the bed to take more rest...

Weiwei posted @ 20:36:51 || New Haven, CT ||

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Thu, September 16, 2004

Growth and Characterization of Model Oxide Catalysts [Research]

A new paper is submitted, which is entitled "Growth and Characterization of Model Oxide Catalysts". This is an invited paper for Eric and will be published on Jounal of Electron Spectrum and Related Phenomena. You can see the draft of the paper in pdf format in research.

Weiwei posted @ 19:33:16 || New Haven, CT ||

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Tue, September 14, 2004

System Down [Research]

The research work does not go very smoothly in the past a couple of months. It's getting worse recently. Today both the MBE and the STM chambers are shut down.

It's not a big deal for STM. We found a leak on one of the flanges. Hopefully it will solve the problem of the ever-bad vacuum in this chamber. For MBE chamber, the heater is broken. I think there is nothing wrong. It's just its time. It will take couple of weeks for the new heater to come.

There is no idle time in the lab. I will keep it up and make things rolling.

Weiwei posted @ 20:54:54 || New Haven, CT ||

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Thu, August 19, 2004

Anatase TiO2 (101) [Research]

Today I got more results from Brookhaven National Lab about my anatase TiO2 thin film. This is a surprise to me because the results I already had are not very good. But what I got today is very beautiful.

From the above transmission electron microscope (TEM) image, you can see both Ti and Al atoms very clearly. Also the interface between the film and the substrate is very clear.

However on the other hand, analysis of TEM image is difficult. In most cases, you can not derive the real structure directly from the image. Because of the diffraction condition, some of the atoms may not be seen from the image. Also the structure alos depends on the orientation of the material mount.

With this image, I could get my paper much better than what it is now. The resolve of the interface structure will go to a seperate paper.

Weiwei posted @ 20:55:06 || New Haven, CT ||

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Wed, August 11, 2004

High Vaccum in STM Chamber [Research]

Finally today the STM chamber in the Becton Lab has the pressure of 9x10E-10 torr. This is the first time it has this low working pressure since it was initially set up about 4 years ago.

The system I am working on has three connected vaccum chambers. I still remember how much effort we had made to find the leak for the MBE chamber, which took about 3 months and got to 2x10E-10 torr eventually more than two years ago. The STM chamber took longer because the electronic parts inside the chamber can not bear very high temperature. We finally figured out the way of how to do it.

Weiwei posted @ 11:01:11 || New Haven, CT ||

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Tue, July 20, 2004

Imaging WO3 (100) Surfaces [Research]

I started MBE (molecular beam epitaxy) growth and surface studies of WO3 (100) several weeks ago. Today, with Eric's help, I obtained my first atomic resolution STM (scanning tunneling microscope) image.

Tungsten oxide (WO3) has wide application in industry, especially in catalysis industry. The (100) surface will adopt several structures, dependent on the preparation procedure. From the large scale image, you can see the atom rows are in a 'framed' strucutre and form a zig-zag shape. The zoomed in image is showing the tungsten atoms.

Weiwei posted @ 22:16:11 || New Haven, CT ||

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Tue, June 22, 2004

With Professor K. L. Cheng [Research]

In today's meeting, I met Professor K. L. Cheng. Actually I did not know him before this. All happened because we sat at the same table.

Professor Cheng is in aquatic chemistry. After the war between China and Japan in 1945, he joined an exam hold by the Chinese government then. He did very well in the exam and was selected to go to US in 1947. Since then, he has worked in electrochemistry for more than 50 years and this year he is 89 years old. Two years ago, he proposed the idea of "triple layer" in chemistry, which is now challenging some of the basic concepts in aquatic chemistry. And just because of this, his theory has not been widely accepted.

What is amazing is that Professor Cheng is still doing research, funded by his own retirement savings. I might not quite familiar with his contributions to the research field, but I admire his spirit of devoting himself to science.

Weiwei posted @ 19:36:41 || New Haven, CT ||

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Mon, June 21, 2004

ACS Meeting at Yale - Cont. [Research]

In today's meeting, I met Professor John Fenn, who won the chemistry Nobel Prize last year. He was a professor at Yale before and even worked in the lab where I am working now.

I am always wondering how many people are doing research for fun. I think today's science has reached a point which is super specifically professional, quite different from the idea of "searching the truth for fun". So it's very good to hear somebody saying :"oh, science and engineering are so much fun!"

Weiwei posted @ 14:48:00 || New Haven, CT ||

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Sun, June 20, 2004

Weekend Update - ACS Meeting at Yale [Research]

This year is the 78th American Chemstry Society meeting of Colloidal & Surface Science, hold at Yale.

I heard that Yale's engineering was very good 50 years ago. However, due to the misleading of Yale's president at that time, it became a very small department. In recent several years, Yale's engineering has made great progress and become larger and larger.

One thing that worth noting is that Gibbs was from Yale. Anyone knowing even a little bit of science should know Gibbs, who made great progress for thermodynamics and even for the modern science. So it's quite surprise for me at the beginning when I knew that Gibbs and I are actually shoolmates...

I gave a talk today. It went pretty good. I am think to build a new section on this website for the academic literature. I will be thinking how I can do that.

Weiwei posted @ 22:06:14 || New Haven, CT ||

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Wed, June 16, 2004

A Little Bit More Progress [Research]

Another paper is submitted today and I am second-authered. Great thanks for Min and his thorough work. I really appreciate that he gave me the chance to work on part of it. Here is the link to the paper.

Weiwei posted @ 21:48:03 || New Haven, CT ||

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Sat, June 05, 2004

Treatment of WO3 Surface [Research]

This illustrates why I decided to add a category for research. Since Wednesday, I have been struggling to treat the WO3 surface so it will be smooth. All I did is to heat it up to very high temperature. But it can not go too high otherwise it will be damaged. Since I do not know what is the right temperature, I have to try from a low start point.

Finally after several days trying, I made it good, showing by the LEED pattern.

p.s. Today (Jun 7th, 2004) it is confirmed by STM that the long time anealing did improve the WO3 surface.

Weiwei posted @ 21:25:08 || New Haven, CT ||

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What I Am Doing [Research]

Frankly speaking, when I started to build up this website, my intention is not purposely for presenting my research work. Does research have fun? I have to say YES. But this does not apply to the people who are not doing the same thing as I do. So I did not spend too much time on the pages about my reseach work.

But I realized that this is not right. In order to make the website, which in my concept is the expression of my life, abundant, there is no reason to exclude the work on which I spend most of my lifetime.

But I will make it simple, at least looks simple. At least you know that I am doing research besides taking pictures and playing underwater. Sounds reasonable?

Weiwei posted @ 21:17:37 || New Haven, CT ||

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