We e
xploit new advances combining mass spectrometry and laser spectroscopy to access interesting molecular properties that are often hidden in ambient or bulk measurements.  

We intend to use this capability to advance problems in atmospheric chemistry, catalysis, nanoscience, gas phase reaction dynamics, and fundamental physical chemistry.  Our work is supported by the following organizations:

Check out the menu to the left for info on the lab and some fun science stuff!

This page is constantly being updated.  Check back often for new info and site improvements!

September 2018
Our new paper, "Direct Link between Structure and Hydration in Ammonium and Aminium Bisulfate Clusters Implicated in Atmospheric New Particle Formation," has just appeared in The Journal of Physical Chemistry Letters!  We show that hydration of new atmospheric particles can be explained by a simple accounting of the cluster structure, and that these clusters are likely to be at least somewhat hydrated in the atmosphere.

August 2018
A big month for the group.  Hanna wins the Outstanding Student Poster Award at the 2018 ACS National meeting in Boston, and Anthony gives a talk in the Inorganic Spectroscopy session, both on the first results of our nano project.  Chris goes on a tour of Europe, visits colleagues at the University of Helsinki, and gives talks there, at Kaiserslautern, and at the conference "Towards a Molecular Understanding of Atmospheric Aerosols" in Bad Honnef, Germany.

July 2018
Chris presents a poster on our recent work on new particle formation at the GRC on Molecular Interactions and Dynamics.

May 2018
We welcome Monica Passananti from the University of Helsinki who visits us for a week to look at hydration of new atmospheric particles!

April 2018
Hanna presents her first results on nanocluster synthesis and tandem mass spec in her poster, "Isolation and Characterization of Gold Nanoparticle Surface Stabilizing Species," at the Scientista Symposium in NYC.

March 2018
Emily gave a talk at the Spring ACS Meeting in New Orleans, entitled "Probing the internal temperature of cold trapped ion-molecule clusters."  Kathy presented her poster, "Acid-catalyzed CH activation in atmospherically relevant clusters," as well!

February 2018
Our first paper, "The Interplay between Hydrogen Bonding and Coulombic Forces in Determining the Structure of Sulfuric Acid-Amine Clusters," has been accepted at The Journal of Physical Chemistry Letters!  Check it out!

Chris gives a hot topics talk at the 2018 GRC on Molecular and Ionic Clusters, "Linking Structure and Growth in Atmospheric New Particle Formation."

January 2018
Welcome to new graduate student Hanna Morales Hernandez!  Hanna will be working on the electronic structure of gold nanoclusters.  A sad goodbye to Dr. Sarah Waller, who after an extremely productive postdoc starting up the lab, has moved on to make things that go into space at JPL.  Good luck Sarah!

December 2017
This site has been updated with explanations of our research projects and experimental techniques.  Check it out!

October 2017
We welcome Dr. Anthony Cirri to the group!  Anthony is a postdoc who will be synthesizing and performing mass spec and spectroscopy to understand how ligands interact with metals in gold nanoclusters.  It is a brave new world for him and us!  We even have a small synthesis lab now. . .

August 2017
Eleanor presents the results of her research in a talk at the Fall ACS National Meeting.  Best of luck to Eleanor, who has headed off to U.C. San Diego, and Jamie, who's headed back to Rhode Island.  Thanks for all of your hard work!  Hello to Thomas Schinkel, who joins us for the next two years working towards his Master's degree.

June 2017
We welcome Jamie Butalewicz to the lab for the summer as part of the Stony Brook REU program.  Jamie will be helping us develop gas-phase ion chemistry and H/D exchange capabilities!  We're also happy to receive funding from the ACS Petroleum Research Fund for work on the fundamentals of CH bond activation!  Finally, Chris talks at the 7th International Workshop on Electrostatic Storage Devices in Lyon.

May 2017
Congratulations to Kathy Nickson, who was awarded an ACS Division of Physical Chemistry Undergraduate Award in Physical Chemistry! Kathy will spend the summer at Indiana University as an REU student, using photoelectron spectroscopy to understand the electronic structure of metal oxide clusters.   Christina Kimotek graduated with her B.S. degree and will be starting her Master's degree this fall. Congratulations, Christina!    Chris is grateful to the Air Force Research Laboratories Plasma Chemistry group, and especially Al Viggiano, for the opportunity to talk about new particle formation and to see the labs.

April 2017
Eleanor Castracane successfully defended her Master's Thesis on April 17, 2017. She will be starting her doctoral studies at the University of California, San Diego in September. Congratulations, Eleanor!  Chris presents new results on new particle formation to Brookhaven National Lab's Aerosol Chemistry & Microphysics group.

February 2017
Sarah Waller serves as chair of the 2017 Gordon Research Symposium on Gaseous Ions, and gives a hot topics talk on our recent results in atmospheric new particle formation at the corresponding Gordon Research Conference.  Nice work Sarah!  Chris presents a poster outlining our upcoming metal nanoparticle spectroscopy experiments.

December 2016
Congratulations to Pengyan Liu, who graduated with her Bachelor's degree in Winter!

October 2016
Chris has been awarded a grant from the Young Investigator Program at the Air Force Office of Scientific Research.  We will be using our composition-specific spectroscopy techniques to probe how metal nanoparticle surface chemistry affects electronic structure and charge and energy transfer.  We're very thankful to the Air Force for supporting this project!  Announcement  SBU Press

September 2016
We welcome Stony Brook Undergraduates Kathy Nickson and Christina Kmiotek to the lab!

August 2016
Routine vibrational spectroscopy is now underway in the lab!  Our first investigations of atmospheric new particle formation have begun!  Thanks to Aakanksha, who in 7 weeks set us up with a computational framework for exploring the structures of these clusters.

June 2016
A busy month for the Johnson Lab.  We are grateful to the National Science Foundation for funding our project on the molecular underpinnings of atmospheric new particle formation.  Also, our instrument is working!  Finally, we welcome Eleanor Castracane, who will be completing her M.S. with us, and Simons Summer Scholar Aakanksha Saxena, who comes to us from Scottsdale, AZ for seven weeks.

May 2016
Our tunable IR laser system is installed and producing prodigious power, and our cryogenic trap is at cryogenic temperatures.  New data is imminent!

February 2016
Our permanent lab space has been renovated and we're moving in!  Check the photos page for our progress.

January 2016
We're happy to have graduate students Yi Yang and John Kreinbihl joining the lab this semester!  

November 2015
We've been hard at work and recorded our first reasonable orthogonal acceleration time-of-flight mass spectrum!  Almost ready for lasers now. . .

July 2015
We're also happy to have Pengyan Liu joining the group for the summer and the upcoming school year.  She will be graduating this year and is completing her senior research thesis with us!

June 2015
We welcome Anthony Chiarenza of Swarthmore College to the group for the summer through the NSF REU program at Stony Brook. Anthony will be helping us build and optimize our tandem time-of-flight mass spectrometer for our laser spectroscopy experiments. We're looking forward to a fun and productive summer!

May 2015
We got our ion source built and recorded our first quadrupole mass spectrum!  Great work everybody!  This source will be used to generate the molecular systems for our laser spectroscopy experiments.

April 2015
Chris and Sarah had a great time serving as judges for the WAC Lighting Foundation Invitational Science Fair in Port Washington, LI. All the projects were truly impressive and made us wonder what we were doing in high school. . .

February 2015
We're also excited about Emily Racow joining the group as our first graduate student!  Welcome Emily!

January 2015
We're excited to have Sarah Waller join the group as a postdoctoral fellow from Indiana University.  Sarah brings along considerable experience studying reactivity in heterogeneous systems and clusters.  Welcome to the lab!

August 2014
The lab is established!  Check the Photos page for updates on our progress. . .