1. Department of Chemistry, Colorado State University, Fort Collins, CO, USA
2. Department of Soil and Crop Sciences, Colorado State University, Fort Collins, CO, USA
3. National High Magnetic Field Laboratory, Ion Cyclotron Resonance Facility, Florida State University, FL, USA
4. Rocky Mountain Research Station, U.S. Forest Service, Fort Collins, CO, USA
5. Chemical Analysis & Instrumentation Laboratory, New Mexico State University, Las Cruces, NM, USA